Zoology. - "'Tec!mical e.cperiences in the bj'eeding of l'eneb)'io ))Iolito?'''. By S. A. ARENDSEN HEIN. (CoITlmunicated by PJ'of. J. W. J\IloLL).

Transcription

1 i j '4 19 As further 1, - l'elatin becmes J- 1y = -, where ). represents tbe melting heat, this t dp, )., dt vt elp, is negative. We have thl1s a sinking f the melting pint and tbel'e is n smtic pressure. The smtic actin appears nly when aftel' having prevented the vlume frm incl'easing we bring, the whle system int semipermeable cnnexin witb a slntin f the riginal cncentl'atin 11\ and unde!' the vressure f the system. The presslll'e in this whle system incl'eases everywhel'e and in all directins by an amunt just equal t - dp, (a psitive amunt). Except fr tbe sign the frmula fr the sinking f the met.ing pint therefre becmes the same, r, when dp is written fr the increase f the smtic pressure, Zlgy. - 'Tec!mical e.cperiences in the bj'eeding f l'eneb)'i ))lit?'''. By S. A. AREDSE HE. (CTlmunicated by PJ'f. J. W. J\lLL). (Cmmunicated at the meeting f April 3, 19). Studies n val'iatin in Tenebl'i mlitr, f which the l'esults are published in the.jurnalf Celleties, gave ccasin t nake sme bsel'vatins with respect t the pmetiee f the breeding f tbis insect. Thugh these faets are nt very suitable 1'1' being tl'eated in a genetieal peridical, as they deal e8pecially witlj teehnieal paj'tieulal's, 1 thugbt their publicatin t be f same value fr thse wh wish 1, experiment with this beetie. COTETS. 1. Chice f the culture vessels.. The fd. 3. The number f mults f the lal'va. 4. The infeetin with TYl'glypllUS farinae 5. The gathel'ing f Plpae and beetjes. 6. The gathel'ing f the Eggs. 7. The mol'tality. a. amngst the Eggs. b. LUl'vae. c Pupae, 1. Clwic'e f the culture vessels. Larvae. Fr the cultlll'e f lal'vae, g'lass erystallizing Jàl'S are pl'eferable t any tlwl' kimt Frm these jars with theit' perpendieula!' slippery wall the lal'vae eannt esè.ape. POl'eelain pts wi th pel'pendieulal' smt lt walls als gi ve satisfaetin. l'in bxes with lids nt fitting ta else (1'1' the air cil'eulatin) are serviceable n,)' when the inner wall is pel'feetly srnth (nt varnished Ol' painted), withut any rust-stains, Rlder Ol' rugh enneeting seam, 8 th at the lal'vae laekany supprt in el'awling up the wall. Tbe fulfilmen! f rhese enditins is f great imprtanee when the perfect purity f t.he cultures itl aimed at. Clfle attelltioll sllould 13 Prceedings Ryal Acad. Amsterdam. Vl XX.

2 be paid 1, 194 these cnditins in rdel' 1, pl'eclude nnpleasant surprises. Glass jars gllat'ftlltee against any disappilltment. As the lar\'ae thl'ive bettel' when the layel' f fd is lt t thiek, the quantity f larvae tbat ean be aecmmclated in a vessel depends n the size f the bttm rutljer than Oll the eapaeily. As a minimum abut sq, eentimetl'es (3 Ol' 4 sq. illrbes) shuld be available fr evel'j' 1 lal'vae. 11' a ql1iek grwth and earl,)' pupatin the fd is t be renewed at set times. The need f a renewal becmes elear frm the erumbly pwdery state int whieh the scaly strlle/ure f the brafl has passed. The renewal is brllght abut mst effectively by sieving A suitable fol'm f sieve S follnd amng the ernmn ki/ellen lltensils (ef. sketcb). The material is usllally tin, the inner side alld bttm smth, the latter (n wi 'e-sieve) pel'frated vvi th 'und hles f r 3 millirnetl'es diameter aeel'ding t tbe siz(!, f the lal'vae. By shaking the sieve hol'izntally alld qllickly, tbe larvae J'emain in a hol'izntal psitin, have na Oppl'tunity f 8l'ecting themselves and are left bebind n the bttm, even when thair thiekness is smaller than tbe diameter f the hles. n less than n time a large cultul'e f srne tbusands f lal'vae call be sepal'ated frm the bran and prvided with fresh rd. F' cultures f whieh tbe lal'vae l11'e ver,)' small yet, very fine wire-sie\'es shuld be lsed. This praetîee ShOllld, hw8\'er, be stpped as Bn as pssible as tje fd, defhed by faeces, is nt suiiciently eleal'ed by these fine sieves. Thc larvae jars were cvel'ed with a glass plate. By gllleing tw strips f thick cal'dbal'd fil'mly n this plate, an inlerstice is left bet ween the 'im f the jar and tbe glass plate thl'ugh which pening an adequate ail'-eireulatin ean take place. lf these cardbal'd strips are laid lse, and if by shving away Ol' remving the jat, sneh a strip falls with ne end int it, the larvae immediately utilise it as a bridge t escape, alld befol'e ne thinks f it, the jar is empty.. 'l'lze /i'd. Relying n the statement ecuting here and there in the literature (FHEZlfL p. 98) n this subject t the effect that bran Bbllid be a snfficient fd fr lal'vae, bran was given at the utset. Theil' gl'wth, hwever, was nt satisfactry. Then a substanee entainiljg 191) mre fat, in the frm f rnsk, was added by way f trial. Accrding t tbe lumber f larvae ne r mare wble l'usks were put in be larvae jars. Tbe creatures Lk hern with eagerness. Ft' cmparisn same ther jars were pl'vided witb sme slices f peat. Als unde!' these, tbe lal'vae gather up and they make large passages in be peat. t is nt prbable that the peat ShOllld serve thern fl' fd. Aftel' th is experience tbe fllwing cmparative experiments vvere made. Six jars were pt'vided vvith:. 1 nly bran (il.). bran all a layel' f peat (B.P.)., 3 nly meal (flur). (LVl.).. 4 meal (flu!') n a layel' f peat (M. P.).. 5 bl'an with 1'lsk (B.H.).. 6 meal (flul') wi th l'usk, (M.R). n eaeh jar 3 eggs were placed in the same pel'id (Ma}' 7-- Jun 1 :l91il), Dwn t Febl'uary 1, 19Hi included, the fllwing numbers f pllpae were cllected: umber f jar Fd. B. B. P. M. M. P. B. R. M, R. TABLE. umber f Pupae umber f clleded till Pupae in Per cent. f the larvae % rm the fregi ng figlll'es, t hngh prvisinal, t he fllwing cnelusills may be drawfl. 1. An exclusive nutl'itin f bl'an is inadequate t a nrmal grwth f the larvae.. An exelusive nntritin f meal is bet tel' than bran alne. 3. An additin f 1'lsk t meal Ol' bran pl'rntes the develpment f the larvae ensiderably. 4. An additin f l'llsk gives a bettel' l'esllit t brall than 1, meal; the plpatin is 4 pel' cent highei'. Tbis pl'visinal resllit was agaill tested in tbe fllwing man nel'. 13*

3 ō :: Q) È l\1 'ëil :>...l t ;...l ; i--, 'ëil - f- < 'Ö ; «Q).-< Q Cl:) :>, M..., 5 :::: 'S Ol :: :::5 -<. 'Ö -Ol «Q) Q c M p.. :: <.:;:: r- :::: :.::l, _ 196 ;::: ---': -.,. Cl') <::> '<j< 197 On the 1 l ], f Febl'uary 1916 tile lal'vae f. 1 (8) alld n. 3 (!V) were sieved, and each grllp was divided inf tw balves f an equal nnmber f laevae. The same prcess was applied t. (B.P.) n April, The 6 grups f lal'vae \,,'ere put in sepal'ate jars. T 3 f these (half f each grup) rusk was added; the 3 utber jars kept the ld fd withut l'usk. On April, 1916, i.e. 69 days aftel' the abve-mentined divisill, the pllpae clleeted frm the sllb-gl'ups f, 1 wel'e cunted, and n J uly 8, '1916, i.e. 48 days aftel' tbe divisin, the pupae f the sllb-gt'oups f. 3. Tile gl'oup. had nt yet yielded any pupae. The rernaining living larvae were weighed n a chemical balance. The l'esult f this is shwn in tbe fllwing tabu lat' staternen t. Here t, t.he fm COYClllSins dl'awn fl'm tlje fit'st experirrient (Tabe ) may be maintailled unabated. That the additin f 'nsk t meal is very effective is manifest, nt nl,)' frm the mre numel'ous pupatin (3 % mre), but als fl'm the abslute weight f the l'emaining lal'vae, which fl' M + H is neael.}' twice as gl'eat as fl' M alne, The enrmolls difference in the mrtality f the la1'vae is als remarkable. ::::: dj :Ei Cl:': Cl:': Cl:':.. + 'Ö C\l cel + ::E + + Q.., cel ::E cel re,, + c <. - :: >... Q) Q) <.:> n ll. «Ol :>.....: - r... E ::l «. Q) Z...l... - =, Ol p..1 ll.n < _. Q).... C(j E...., b c U ntil nw the rusks had al wap been added unbrken. A special l'easn gave ccasin 1 pntting tbe questin whether 'nsk wuld perate as favlleably if rednced t dust and mixed with the bran. fildeed, frm fol'mer 6xperiments (nt llndertaken fl' fd pllrpses) thc experience had been made (hat lurvae fed exclusively n pul\'erised l'usk (rusk rneal), d nt grw, and many die. The increase f the bdy weight f the larvae fed n l'usk alne arnunted t 48 % in 43 c\ays with a ml'tality f [he larvae f 38 /, whereas tbe figlll'es fr the arvae fed n bran appeal'ed t be 117 % wilh a mrtality f nly 1.5 %' The fd expel'iments were therefre cntinued with the fllwing mdificatiolls. The 118 lal'vae which rernained n (he th f April 1916 f experiment. 1a. (cf. Table, COUl1n 7), i.e. arvae fed exclusively n bran, were again divided int tw eql1al hah'es, each f 59 larvae. With ne f these hal es the ld way f feeding (ny bran) war kept up, the the1' half received bran + ruskmeal. On the 8 th f Jnly 1916 the larvae f blh grllps were remved and weighed n a chemical balance. Pupae were nt gathered fem these grnps between April and Juli 8. (Tabe l). The result btained was as fllws.

4 TABLE 111. umb. f Remaining Mrtality f Weight f Larvac Larvae Larvae Fd n July 8 Larvac n in milligrams n , , April Living Dead 1 Larvae Ttal taa.la 1 59 B Uf a.la 1 59 B + Ruskm t is bvius that the additinal fd administered in the frm f plilverised (gl'und) l'usk has perated very favu'ably, and in general n less t.han in tlle xperilllnts with llnbeken t'llsks. (Tab e ll. S fal' tbe expel'iments n the infnenee f rllsk (fat.) as additiflal fd. w t.he qlles/ih bad t be sttled whethel' bl'an, Ol' blted meal (fm) ei/hel' with Ol' withut theadditioll f l'usk, is f eqllal nutrit.ive value 1 tlla lal'va. Fl' tbir pnrpse it is lecessal'y 1 revert t the jal's U.4 (M.P.). 5 (B.K) and. :) (M.R.) mentined in Tabl. F!'m these grl! ps th fjlwing 111lbei's f pupae had tt/ready be ell gatbel'ed n the Feb!'. 1, 1916 (as stated in Table ) frm. 4 (M.P.) 13 pupae.. 5 (H.R.) (M.R) 36 The ellecting f pllpae was cntïflued til!.lnly 8. Then the expel'iments were elsed, tbe cllected pupae eunted, the mol'tttlity f' the larvae figul'ed ut, alld the remaining larvae weighed. This yielded tbe fllwing resnltr, als including thse f experiment. a (f Table J), which may sen'e fol cmparisn. TABtE V. '... c Pupae gathered Remaining Weight f the Q)... 'Cl Larvae (j) E Larvae in m.gr... ï':: Q) E w.. ::l n. Tatal. Living Dead. Tata!. Per i><: Z Q) Larva. 5 (tab. ) B. R % % (tab. ) M. R a (tab. ) B. P (tab. ) M.P Fl'm tbe abve figmes it S evident that bntl1 with l'usk a additinal fd had a rnueh mol'e favllrable effect t.han meal + nwk;, the pnpalin is '1 highel', the rnl'tülity f the lilt'ro is eqnal, the weight f the rernainillg lat'vae is 38 miligmms pel' larva mre. This result enld nt be expected wben at the nl8et it appeared (cf. Table 1) t!tat la meal and bmn withut any additin, meal was preferabe ; the additin f rusk shws tbc ppsite, alld this witb ralhe!' stl'ngly telling figul'es. t is prbably nl,)' the fat and the ajbllmin f the rusje that have perated s favurably. JDspecially fat is nly scalltily follnd ill bran and meal (± 1,6%)' whel'eas the l'llsk nsed entailled 8.9 %_ Surnmal'izillg the l'esults f' these 1111tritin expet'iments, tltey may be wrded tbus: 1. Excillsive meal rd is pl'eferable t exclusive bran fd.. Rnsk as additinal fd t meal as wel as t bran always has a \'el'y favl1l'8ble inflllence n the grwth and the quicker develpment (pupatin) f the larvae; tb is hlds gd fr l'usje in an unbl'ken OL' a gl'llnd stat.e alike. 3. Tbe mst favurable l'eslt!ts (mre pnpae, and lw mrtality and high weight f the lal'vae) were btained by a mixed nutritin f bran + l'usk. 4. Gl'lilld l'usk as exelusive fd 1'1' lat'vae is perfect!y unsuitable. The mol'tality is cnsiderabe, the increase in weight small, the pupatin is stpped. 5. Tbe additin f slices f peat t meal Ol' bran has lo inflnence n the grwth f the larvae, and is wol'thless as fud. Peat seems t have a direelly Ol' indirectly nxius effeet; the mrtality is abnrmally high. 3. l'he nttrnbe1' f rnults. n the literature (131mHM p. '18; FRiSCH vl. p. 1 ; SAUG p. /8; S'l'UHM p. 1/) it is always stated, that thc larva muhs fur times, and that aftel' the folll th mult the pllpa appears. Apparent,)' tbis statement has nevel' been entrlled, fl' a simple experiment wuld immediately bave shwn, tbat it is false. A lal'va was put in eaelt ne f a series f lllllbel'ed small pts filled witb fit fd. Tbe larvae were at mst nfl r tw days ld, and still w hite in cu!. At fixed times these pts were searchen fl' mults. The h'st mults are nly t be fund b,)' cal'eflilly spl'eading ut the fd, and examining ij with a lens. twithstanding a else inspectin they smetimes escape ntiee, becallse they are ften n langer intact, and brk en!lp int smaller fl'agmentr, s that they are n lnger t be rcgnized as mults.

5 i il Therefre the nnrnber f mnlts, given hcrcaf/cr, is ne Ol' tw mnlts mre rat bel' than less. Whcn thè larvae have grwn largel' and all'cady shw Et distinct 1rwn clul', these molllts are casier t find; genemlly they lie n tbe slll'face f the fd then. The investigatin gave tbe fllwillg result. During the first perid f stl'ng gl'wth Et mnlt rnay be expected every fol'tnight; afterwards his l'egnlarity ceasetl.. J gave:j1 rnnlts; lal'val pel'id 4 days; died Vl'itbnt pupaûn.. gave J molllts; Jal'val pel'id 1 \:)4 days; nrmal pupatin.. 3 gave 1 mujts; lal'val perid194 days; nol'mal pupatilt.. 4 gave 16 m(hllts; larval perid 4,5 days; nrmal pupatin. Larva. 5 gave 16 tlnlts; larval perid 376 days. Tbe investigatin was repeated nce mre with 8 Jal'vae, all f tbe same mther and f the same age. Dates f the gathering. 9th f vember 1918 ) 8th 13th December 9th 11 15th Jalluary 3lth 14th February 8th 14th March 3th 13th April 3th 14th May Ttal f mults 1919 Duratin f larval perid in days. ) Date f the just emerging larva. ) 6th May umber f gathered muts frm Larva 1 _1_... 1) l The dates, 11 wbich the mults were gathel'ed al e als nted 111 the list befre. 4. nfectin by l:jtglypltus farl:nae. TYJ'glyphus farinae is a small mile stl'ngly tlattened dol'sventrally, abut OA millirnetl'es lng. The eggs f tbis mite seem always t be present in meal Ol' bran, t devejp ny llflder definite eircumstances, f which misture 8eems 1 be the mst impr1ant factr. t' tbe cnditins f life are fallrable t tb is mite, the multiplicat in may be 8 enrmolls that the whle layel' f brart r meal seems t have changed int a hrngenells mass f TYl'glyphus. 11; is true that this mite des nt infest the larva, still tbe gl'wth f tbe lal'vae is collsiderahly illjul'ed by the withdl'awal ffd. Tbe develpment f the pllpae gathered frm a jal' infected witb Tyl'glyphus, als suffet's gl'eat distnrbances by this mite. n clse little heaps it nestles between and bebind the legs, wings and antennae, and canses defrmities f these l'gans in the later emel'ging beetles. The reseal'ches witb respect t Tenebl'i were started in the spring f 1915 and cntinued withut any incubatrs thl'ollghut the summer. Thc mite tir'st made its appeal'ance in 6 cultures at the same time, and that in jal's whieh bad been pllrpsely placed ill very damp surrundings; tbe develpment and llultiplieatin f tbe mite in these jan was s intense that these cultures had t be dne away with. Later n a similar expej'ience was made witb several thel' cultures standing free in the labl'atl'j', when a spell f humid weathel' came. At fil'st there seerned t be 11 bet ter means than insulating these vessels frm the rest. Tlte necessity f his insulatin t prevent all the cultures fl'm being infected within a shrt time, is apparent frm the fact that the infectin paf>ses frm ne jar t anther in spite f their being cvered with a glass pjate, lying directlyn the rim. Tbe mite crawls up the wallf the glass, and tries t get ut between the dm and the cvering glass plate in whieh it genemlly sueeeeds, as there is always an interstice wide enug'h t allw its flat bdy t pass thl'ugh. Tben an expedient was tried, which was efficacius s far as t preven t an infectin frm passing frm vessel t vesse!, even if they stand uncvel'ed side by side. At abut centimeters belw the rim a ring f vaseline was applied illside. Thrngh this greasy substanee the mite cannt get and tbe infectin

6 remains lirnited t the jar in Cjuestin, especially if the vaseline ring is thiekelled frm time t time. But restricting the extentin f th illfeetill is but an indirect meastll'o against the evil, whieh rmty smelimefi assllrne large dirnellsins, when its appea,rance must als he aeelljlted fr by the bad quality f the malal' the bran lsed. Tbe expel'ienees in his matter were at the ntset sa disappinting as t almast discllmge any fmther investigatins. S it stands t 'easn that with great satisfactin the experienee was made that all at nce everything cbanged fl' the better fl'rn the flament whell the cultures were transfel'red int incubatrs with a temperatllre f ± 5 Celsius. Tt smetimes ccurred, it is true, that herg and there the mite appeared (espeeially ijl humid weather), but by a general applicatin f the vaseline ring, a srler Rieving and renewal f the fd and an ceasinal raising f the tempel'ajure t 8, th situatin enld be kept uldel' entrl, sa mneh sa tbat TyrgJyphus fal'inae was na langer a fol'midable enemy. 5. The Gathel'ing f Pupae and Batles. When ihe pllpae make theîl' appearanee, tbey sbuld be 'emved. Even if ne des nt wish t sart them int males and Cemales, anc bas bettel' nt wait (1'1' val'ius l'easl1s) until tbe beetles emerge, When the h1yel' f bl'an is nt ta tbiek tbc pupa wrk themselves up t the slll'face, either wllolly, Ol' padially, sa thai nly the distal end f tbc abdmen sticks ul abve the bral! laycl'. Thc sidelng hradened latral edges f tbe seglllen ts 5 1, 11 inel. (Fig, Hl) are pl'vided wil h 3 Ol' 4 sharp stings and wndel'fully adapted t render this wol'king up pssible easily aud quickly. Tha, these bl'adened lateral cd ges with theit' stings are nly serviceable in the pnpae stage is apparent frm the fael that his edge with tbe stings is east ff tgether witj tbe pupal skin and des lot return in the beete. At a temperature in the incubatr f 5 C, the larvae jal's may, aftel' tlte last gatheeing f pupae, stand 7 days, befl'e tbey l'equil'e t be inspected 11 pllpae again. At the temperatut'e mentined the develpment frm pupa t beetle takes abu t 9--'1 days. Tbe pllpae elleeled were pilt in deep saueel's f a diameter f abt. 13 e.m., the bttm f whiclt was evel'ed with a pateh f blaek sateen. As sa n as Lbe beetles emel'ge they crawl, shullning the light, unde!' the patch l' tbe enrled-up brders f it. Tbe nllmber f cast muus that 'emain n the saleell, dentes the 111lmber f' beetles th at keep in the shade smewhere. 3 lf the beetles need lt be gathel'ed daily, a piece f rllsk ShOlrld be laid undol' the pateh. Tf na rd is ffel'ed them in time, they eat he pu pae. Tlte pupae dishes were cvel'ed with a glass plate reaching beynd the l'irn. n tltis way they may be pijed up in the incubatrs, wilije any eseape f he beetles is preelndecl. 6. Gathe?'ing the Eggs. The clleeting f the eggs was a maller f 11 smail impl'tanee fr the btaining f a lal'ge psl.el'ity. TlJc ditllclllties tbat we re expeeted, did nt accu!'; the prblem was Rlved ill quite a satisfaetry manner. Tbe beetles emerged in the pupae dirhes are lransfe!'l'ed la the beetlebxes in whieb tbe prduct.in f eggs is awaited. Tbe beetles were kepi in tin bxes willt smtb walls alld prvided witb a ('ve[' elsing nt t hel'metieally. The bttm f the bxes is evel'ed with a pateh f blaek saleen, ijl whieh a few hles have been cut t lel the beetles tbl'ugh, whieh hide by preferenre udel' the pateh. On the lap f the saleen Slla11 pieees f ft wlly materia! are seattered. Tbe e11ice f the quality r his material (egg patches) n which tbc eggs are depsited, is vcry imprtant. On his pint the beetles are ver)' paf'ticlllal' and will nt at all, r nly in a small nnmbel', dcpsit theil' eggs if the stuff is nl wlly [' thready enugh, sa t bat thc eann/' attaclt t be eggs n it. f the stllff is ta thready, the eggs are laid s deep in tllû tissue that they are difficlllt t discvel'. Als SAUG recrds tbis peenlia!' habit f the beetles f depsiting theil' eggs n a wjly rna/ria!. Tbe egg patches had El size f abnt 1 r 1 1 /. e.m'. These smal! patebes are pl'efemble, fr val'ius praetical reasns, t thse f large!' dimensins. As fd fl' the beetles, pieees f rusk were nsed, saked with a few drps f mi k, Ol' fresh ellt pieees f ptat, Of the latte ' the beetles cat all but nthing ; yet the}' greedily fall t them, prbabjy attracted by the humidity f he fd. The fd ia put under the sateen, in whieh the hles serve fr passages t l'eaeh the egg-patches, while tbe sateen, la sme extent, pl'cvents tbe egg-patehes frm being defiled by he faeces f the beetles. 'fhe egg-patehes aee tram;ferl'ed, with the eggs elinging t them, int a ja!' in which befrehand a thin layet' f fd bas been bl'ugbt fr the C'ming yung lal'\'ae. n a ternperatut'e f 5 C. the halehing f tlre eggs takes abut ) Ol' '1 days. 7 H

7 4 WlJen frm a culture a sutncient llumljct' f eggs bad been gathered the egg-patehes were still kept in t.he incubatr days aftel' the last gathet'îng, One is quite cel'tain then that all the eggs capable f develpment have been hatebed. The egg-patches are remved, same fresh fd added in the larvae jal' and t!lis is left t Hself in the incubatr fl' same time. Like the pupae, the eggs were gathered nly nce a week. When a large number f beetles is kept tgethel' in ne bx, tbe banest f eggs is aften 1 sllall in prprtin t the nllmbel' f beetles. f thse same beetles are distribllted ver a sel'îes f small pts, the hal'vest f eggs incl'eases cnsiderably. This fact is illllstrated by tbe fllwing ease. Jl a bx f 1 X 1 em. wer 88 beetles ; frm these were btained respectively 1: :181 and :11 eggs in the last 4 gathel'ings. Aftel' distributing these 88 beetles vel' 8little pts, the next harvest f eggs incl'eased t 468, the nc1 t. 56 eggs, i.e. mre tban follr times the last harvest f the preceding series. 7..lJ11'tality, The mrtality amng tbe eggs, larvae and pupae is as a rule cnsiderabe ; lw mrtality figl1l'es are exceptins. l. Anwng t!te eggs. n the 6 nlltritin expel'iments rnentined n page 195 thel'e were in each jar an equal number f eggs (viz. 8), all f the same l'igin. The diffel'enee between this tigure and th numbel' f yung larvae (living + dead) whieh were colmted at a definite pint f time, dentes the nurnbel' f nt-hatched eggs. T each 1 eggs aid ut, the rnl'tality in thse 6 enltures amnnted. Ft'. 1 1, : On an average 8, 1 The fjgul'es divel'ge rather mueh, whereas a special eause eannt be pinted ut. At fil'st arse the thught f CTOl'S in tbe cunting which was earl'ied 111, by spreading the brat! very earefnlly, bit by bi t. <ti 5 The arvae were, indeed. cunted nly allut a mnth aftel' they had been tl'ansfel'l'ed frm the egg-patehes t the fd, and being very smal, sme might have been verlked, Ta vedfy this melhd f spreading, the egg-patehes, in fut' ther trials, were depsited in empty dishes (nt prvided with fd), and the newly hatched lal'vae cunted and 'emved. Any verlking f the lal'vae was preeluded in this manner, 1'he resnlt f these ful' experiments was as fllws _.. t hatched eggs... -t - -n-- / % ,5 Ttals and mean % Here, ta, there is little if any agreement amng the mrtality figures: The result f these experiments gave n ccasin fr giving up as uureliabe the pl'evius methad f carefully spl'eading the bran in small quantities. 'rhis is why this [ll'ceeding has always been fllwed in the sllbsequent fixing f the mol'tality figlll'es; als beeause ne acquil'es suelt a dexterity in it that an verlking f the lal'vae beerns all but impssible. n the fit'sl tw yeal's the mrtality f the eggs f nearly all cultlh'es was detennined. The fllwing avel'ages were tben btained Year f experiment. Eggs Larvae MrtaJity f egs. depsited. btained. TtaLTn-/ % _....=-1.9_ J_. Ttals and averages in the years, % The abnl'rnally high mrlality figul'e f the expel'imental year : as empal'ed with , is stl'iking. 11'1' this n definite eause Cal be assigned, exeept pel'haps temperatul'e illtluenees,

8 --._._._ û6 as the barvest f the eggs f the yeat' tk place in the spring and the summej', and that f thesucceeding year in the autnmn and the wintel'. The rm was heated, it is tme, and, witll a single exceptin, the cultures wel'a tl'ansfel'rd int the incubatr, but bth the frmer and the laltel' were dne nly when the cld becarne unpleasant. n tlte experiment year he wintel' was sevel'e, with lng cntirllled frsty weather. The fllwing experience was btained. A small sel ies f cultnres, whicb culd nt be accmrndat:ed in the incubatr, std free in the abnttr,r. n tbe daytime tbe rm was heated, and dul'ing the frst it was heated sligh!ly at night t, s that the minimum temperature was never belw 7 C. Tbis is kuowll with perfect eertainty as the temperalure f tbe rm and the incllbatrs was l'egularly lted dwn 3 times a day. Fl'm these ntes it appeared th at the tempel'atlll'e in the early mrning and late at night nevel' sank belw 7 C. f ne assumes, t be eertain, tbat the tempel'ature, at a given mment may have gne dwn t 5 C. befre the thermmeter indicated this sinking, i may be stated as a fact that this tempemture is alrcady deadly t the eggs. n the abve-mentined series f cultures the mol'tality was s high that nly a few eggs wel'e batehed. FJ'm tw jal's, each f which cntained 15 eggs, nt a sillgle larva was gt front ne f them, and nly tw lal'vae frm tbe ther, even aftel' the eggs, which still lked rather nol'mal, had been kept in tbe incubatr fl' a lng time. 'llhis gl'eat sensitiveness f tbe eggs 1 lw temperatul'es, was nt furthel' studied. On anther ccasin tbis eircnmstance will be l'everted t. These bservatins have been recm'ded nly t pint ut that (he abnl'mal mt'tality f the year '19:17 may pssibly be cnnected with temperatul'e influences. The eggs experimented n in that yeal' were distributed ver 5 set'ïes f 11 separate cultures in t/al. n ne series f 7 cultures 45 eggs had been put, and in 4 series 417 eggs in 94 eultnres, Thc ayerage mrtality f tbe (ir'st series wilh 7'cultut'es amunted t 53.7 /' Ft' that f the 4 tber series the figures were nj sel'it's f 7 eultllres 85 eggs witb 3. % dead 3rd th th Ttal 94 cultures 417 eggs with 34.4 / dead. 7 [f ne leaves the abnrmal high mdality f 53.7 % f the fh'st,series ut f cnsidel'utin, tbc avcrage egg mrtality ver the tw experiment years f eggs becumes 3.4 /' As the uteme ne may tberefre assl1me tbat, in general, nl,)' /3 f the numbel' f eggs are batched. b. Tlte?/rtalüy anwn,q the lal'vae. As has been said, the cause f the egg ml't,ality is still uncertain; that f tlle lal'vae mol'tttlity gives mre psitive indicatins. Frtullately epidemics have lt appeal'ed up till nw. S tbey eannt have played a pad in lhe lllrtality figmes mentincd belw. Tbe lal'vae gnaw at ea('l OUlelS bdies and pel'haps they smetirnes eat each thet' up entil'ely; this canniba!ism is, 1 be slll'e, tbe main cause f the lal'vae mol'tality. A srnall percentage ilo! gnavved at, died f lnknwn causes. The lal'vae m/'tality in the experiments years :1915/1916 and 1916/1917 was: umber f La;'. Oead Larvae Maria Year f experiment. vae the culturel lity in 1 was b egun W thl' Larvae. ' 1 arvae : % r ' Ttals and average % HGl'e he ppsite case t that f tbe egg-mrtality presents itsejf, viz. the fit'st experiment yeal' shws a cnsiderably higher mrtality figure than in tbe secnd yea!', A fnetl' thai may have infilleneed th is lies in the cil'eumstance that an additin f thin fresh eut sliees f ptat Ol' cant scattergd OH the fd (enhaneing the hllmidit.,y) bad a speeially fa\'urable effect, nt nly 11 the gl'wth and develpment f the lal'vae, bnt pal'tielllarly n the mrtalit,y f tha pnpae. Wit.h regard t tb is, envincing figlll'es will be snbmitted when the pupae mrtality will be treated. n cnsequence f the 'esnlts btained in tbe early part f 1917, the additin f slices f ptat was slarted late, wben a large part f the ttal numbel' f pupae btained f thai experiment yeal' had beell al ready gatl!ercd. By t!tis t!te late gathered pupae (tgetbel'

9 -,, with the lal'vae) prfited by this additin, bnt, f curse, nt the pupae tbat bad been tben ellected already. Bence the pupae-mr-. tality f 1916/1917 is still very high and even higber tban f 1915/1916. w, tbe cnnectin (alluded t abve) that may exist bet ween the mol'tality figul'es f larvae and pupae appeal's frm the fllwing. When ne allws a numbel' f cun.ted larvae t pupate in a glass jar, and aftel' sme time adds the pupae gathel'ed + the dead lal'vae + the remaining living lat'vae, tbe sum ttal is, as a rule, smaller than tbe number f lal'vae with whieh t.he culture was started. As an escaping f larvae frm tbe glass jars des nt ceu\' (we nevel' fund any lal'vae crawling abut in tbe incubatr since the use f glass jars), tbe laeking lat'vae cannt but have been eaten p.1'his eating-up mst prbably taak place nt in tbe lal'val but in the pupal state, when the newly emerged bdy is still sft. Tbe annihilatin f tbese still sft pupae bas then been executed in a much mre radical manne!' than in the larvae gnawed at, while by the white elul' the fragments f these pupae are much mre difficult t find back tban t.he relatively biggel' remairis f the brwn lal'val bdies. Tbis praetically estimates th mol'tality figllre f th lal'vae t high, and tbal f the pupae t lw. Tbis circumstanc applies mre specially t the year 1915/1916 than t 1916/1917, because in the latter year, as has been mentined, a part f the ]al'vae wre aready prvided with slices f ptat. ''his expedient pt'u!(ed the grwth f the larvae and an eadie!' pupatin, and strngly diminisbed the mutilatin f the pupae; in cnsequence the figllre f the larvae mrtality (by tbe manner f fixing his figul'e) had then 1 decreas. w althugh these influences have, n dubt, asserted themselves,. they were nt f such a natme as t satisfactl'ily accunt fl' the greal difference f the larvae mol'tality in these tw yars. Simiar great diffel'ences appeal' als between the cultures (f lie series) th at have been expsed t equal extel'il' influences f fd and ternperature, and disagl'ee nly in ne pint, viz. in tbe time when the eggs we re depsitd, and in the numbel' f these. c. The mol'talit?l amng the pupae. The mrtality amng the pupae appeal's in the same way as amng the larvae, viz. by gnawing-ff, and by an unjmwn callse by which they dry up r, by way f rare exceptin, becme black, and be bdy remains sft. Besides these pllpae eaten at, als thel's are fund, nt dead but wunded. Tbe humtll' thai has flwed frm the wund is then 9 mixed with the bran and dried up int a lump. Such wunded pupae d nt develp int beetles, bnt die s.ner r later L1 prprtin as the wund ccurs n mre r less. vlt.a Ol ans.. ''he canse f these injllries is alike a begll1mng f gnawll1g by the larvae, frm whieh the yung pupa has been able t withdraw, as it always l'eacts t mechanic stimulatin with vehement mvements. '1'h gnawing away may, especially in yun. pupae, be sa far advanced that nly small l'emaindel's f the ellllll1-shell are fund back. Between these extremes ne tlnds marly intl'mediate stages f mutilatin. With this the mrtality amng the pupae is nt yet at an end. The pupa' has still a critieal perid t pass thrugh, viz: the time shrtly befre easting the pupal mnl!. Same Hlnwn. (hsturbanee r ther during the metamrphsis either ccasons lts death, r prevents a nrmal beetje frm emerging. The distl;rbanee usu[tlly manifests itself in that the wings are defective, Ol' are nt perfectly deve1ped, anel that the pupal mult in the distal part f the bdy is nt l'emved. The legs arc mstly elevelped s fal' th at these pseud-beet les can utilize the yt.. They are wl'etched animas, whieh crawl abut needy anel l1valtd, and die aftel' a shrt time. They have been mentined separately [ts half beetles in urmrta!it.y!ists. 'fhe mdality f pupae gatlwl'ed in tbe yeal's1915j /1917 and 1917 is shwn in tbe table belw.! Pupae gathered. the pupae btained died Mrtality f Pupae in Of. as as as as pupae hatfbeetles pupae halfbeetles Ttal % 1. 8 % 11 % » Ttal and averages T 7-; % % Mre than nee already had been struck by the fact t.la! if laid big pieces f l'llsk, saked with water, in the larvae Jal',. he. ae gl'eedily eat f them. Tlüs fact led me t the supposjtlort arv, 14 Prceedings Ryal Acad. Amsterdam. Vl. XX.

10 ---- -_ _-- - to 11 u; <J. Uï <J Ol ' <Ó '<' - M Cf) '-'-- ' ' ' <Ó - Ó.- Cf) M Cf) lf).- -..::: > '-'._'-.- ' al btj <J r-= :>. è!-.... t; <J... til ::l :> ) ;::l... Ol.-...; t::. ' (Jl <J til <J i:: Q) J.. Ol >- Ol!-. <::> r- <t' <::> < Cf) '@, til ('1 M.-< ->-' ::r:: (- t;-g'o,.c1 Z f' ;;, :; -:n t :,,----=:; tbat the mu(ilating f the pupae by tbe larvac was pel'haps brught abut by wallt f humidity, givell the cil'curnstance that thc fd in the inclibatr dried up mol'e alld mre, until it gt Cl'umbly and was l'enewed. first put ut a feeer by laying large thin slices f fresh beetrts n the tp f tbc fd in a few jars. The utcrne was a smprise. Tlle harvest fl'm these jars prvided with slices f beetrt was nt ny gl'eater, but tlte eating f pupae had dirninished in a stl'iking way. Then tbe fllwing curse was taken, Tw jars were p'vided wilh fresh fd. n eaeh an equal quantity f lal'vae was put. One f these jal's gt 8 slices f beetrt r cal'l't, the ther nne. Fl'm these tw jars 6 harvests f pupae wel'e taken. The results are shwn in the tabulal' scheme befre and 8peak clearly enugh. One will see a cnsiderabie decl'ease f the deathrate in each harvest. The deel'ease is slightest in tbe nd and the 5 th harvest. w it appeal's fl'om ntes made, that in the perids between January 1 and 17 and between Jan. 3 and Febr. 6 i. e. bet ween the jst and nd and the 4 th and 5 th harvests n carl't had been added, beeause the bran still feit vet'y h llmid 1 t he tuch frm the previus time. This after-effeet f tbe hllmidity f the previus additill f slices is yet s gl'eat as t diminish thc deathl'ate in bth cases, in tbe ui <J. Ui... ::J (,') '-S 'Cl <J!-. Q)..c '@ < Cf) Cf)... Ol Ol!) < r- (- 'Cl «i < Ol Cf) >() til <t' btj :;; ' <J Cf) Ol lt:> Cf) Q) til p.. ::l.. bj,... i:: r- <..;;: ld Ol :$ - t t- M ;:ï -,... al fj :>-. til [-: ;>,! r <J ; til :::::! >- ;:::l.-... <J '-' i::. ' (Jl Q) til <J t:: <J... >-; J.. til >- Ol... r-,... <::> < Cf) til Ol.-<... Cf)... ::r:: (- - Z ' _. <l -----_._-----' ' -' -' -' Ol è ::;;. ij:, (6 -.- (- Z r.u :::E 5 r.u p.. :x: r.u <:::> < è <Xl :: \.,. <J J.. <::::> l st by 9 / p in the nd by 5 %' This experiment was l'epeated n anther quantity f larvae, f whieh in the tw jal's an eqllal lumbel' was again depsited. Here, t, the l'esult was again in favolll' f thc jat' 'with slices, f whieh the mol'tality was 1 less than in th at wit/tout eanl (f Experiment r). t is als remal'kable that in bth expel'iments the ttal number f gathel'ed pupae is larger, whieh clea1'1y indieates that the gt'wth f tbe lal'vae is very much furthered by the humidity. wa::; nt quite envineed and stal'led a third trial. then reversed the state f humidity fl' the lal'vae at every turn aftel' a number f hal'vests. Tw jars were eaeh prvided with exaetly 1 larvae. n rder 1 be sure hat these lal'vae were in the same stage f de\'elpment, they were weighed befreband. The weig;ht.s were the same fr each gt'up, viz. 11 grammes. Thc vessels gt he same weight f fd; ne f them gt 8 slices besides, the ther nne. When the fd in the ja!' with slices was cnsumed earl ier (ban that in the tllcr (whieh always ecul'l'ed in all series f expel'i-

11 .._-,, ' l:- lo ?ff!. < t r..: ' >ri <:::> - - ' '<' r- '<' M Cl:) M < M lr') < Cl),... Cl:), ' r..: M '<' CV') ments!:tnd whir,b fact sbllld be particlllarly nted), bth were prvided with fresh fd 1 keep the circumstances as equal as pssibe. Five days elapsed between tw suceessive harvests ; during all the time f tbe experiment the jal's remained in the incubatr. The result f the first 5 harvests is shwn in the table n page 1. As the table shws, thc a\'el'age deathmte in the jal'ujitllout slices was abut 17 % highel' than in tbe ne with slices. The fd was renewed twice, viz. n A peil 1 and 1. n bth cases thc fd with slices had all'eady becme s crumbly that it had t be l'emved. U lldel' rdinar'y cil'cumstances, the renewal f the fd f tbe lher vessel lthe ne withut slices) wuld nt bave been necessary. As has béen said all'eady, this case O(curred repeatedly in all series expel'imented n. At tbe end f the 5 th harvest the lal'vae were sieved and collnted t verify all figures....; til (!) :>... ::r:: r..: ;.- (!)... t<! Cl ' Z.t: Cl.. < ' :- ;::J r- -.lar A. Experiment a. withut slices) umbel' f lal'vae the cultnrewas started with... 1 n the sieve were left 64 larvae living + dead pupae gathered 31 daad al'vae 37 tta! 1 >fl '<' -.Ö... J ar B. (BJxperirnen t U a with slices). llmber f larvae the culture was started with... 1 n the sieve were left 69 larvae living + dead pupae gahlgred 343 dead larvae 8 ttal 1 f- Z gg 5 t.ll.. t.ll <ij til ;;.... cd -l <:::> <::> - til (!).S:! Ui... ::! <:) -cl tl), (J c: 't:ï < <' ti...,..,. Ci t- tl) Cl _._-_... bil \::: r-.:; ' S -t.-- < :.:î --'--'; ,,----- '@ _._ ' Z The subsequcnt series f hal'vests were dealt with as fllws. The slices f ptat were added t th8e larvae that had nevel' enjyed them, i. e. t the 64 arvae f jar A. The 69 lal'vae f jar B, which had always had slices hithert, had t d withnt this additin. The figures f the harvest' f th is series are given in the table n the fllwing page. With the exceptin f the 1 St and the 6 th hal'vest the mrtality tigure fr the jar withut slices was cnsiderably higher again in each successive har vest. That the lst harvest shuld be an exceptin t it culd nt but be expected. The larvae had, indecd, in the frmer harvest, prfited frm hurnid surrundings, and the after-effect f this manifested itself in the nxt harvest in spite f the changed enditin. The 5 % lwer deathrate in the jar witlwut slices des nt therefl'

12 Cl ëa E-<.s:::... Cl r «M dl Cl) fi(j Cl P. bil ;:l c Cl..:; ::ï r..: -.t: >» Cl.. :1.,.J.- ::! (f) <!) :>... k. t<l t') cc cc :1,;j :r: Cl Z '<!' ' -C\.. cc C\ tc') < crj '<!',. t:: ::l..., tc') r..: frm an exceptin, but n the cntrary, enfil'ms the rule that tbe additin f slices caused a stl'ng regl'essioll f the death rale f the pupae. The exceptin f tbe 6 th hal'vest had been bl'ollgbt abnt bj' the cil'cumstance that in cnsequence f the excessive hnmidity in tbe jal' witlt slices, tbe fd had cltted and gl'wn quite muldy, The wall f the ja\' was cvel'ed with big drps f water. 'rhe 7 dead pupae gatrgl'ed had nt been gnawéd at, indeed, but wel'e black. Here the t rnuch f a gd thing, had apparently prduced a l'evel'se effect. The fd f the jat' under discussin had t be renewed fr that reasn, and his was dne in bth vessels, again fr tbe sake f the unifrmity f eireumstances. twithstanding these tw excepuns the avcl'age mrtality f the 9 harvests had fallen by 4 / fr the jar wit/l slices aftel' all. At the clse f the 9 th hal'vest f the abve trial series Uh, the larvae were sieved and cnnted t veri(y the figures btained, with the fjlwing l'esnlt: Ja?' A. (Bxperiment llb withut slices), umber f larvae this series was staeted with 69 On the sieve ware left 398 larvae Living + dead pupae gathel'ed 5 Dead larvae. 6 Ttal 69 C.t: El Cl.. :><: W cci El :>k. «...J t- '> Z tlj :! w Cl. :x: w ui. en J::... :::! bj.5. 'M _ _--,... 'e <lj r r..: cc ; 'e»..., Cl.. r - ' ' Ul :! <lj :>-... til tc') Cl cc cc r... - :r: --.<::.<::.<:: ' i: ::;;. in < ' < C\.<:: t::. c;:;.<:: ê(, =..., ::l >t';.<::. Q) bj r k. :>- :1 'Cl t:: r «i... E-<.lar B. (Ex peri men t llb witlt slices). umber' f lal'vae this series was On the sieve were left.iving + dead pupae gathel'ed Dead larvae. started with. 418 larvae 9 Ttal Mre individuals arcunted fr than there were at the ntset 7 Tbe verificatin f jat' B shws an excess f 7 individuals. Hw the errr bas arisen, is nt knwn. As a rule sneb a vedficatin shws a deficit, as the remains f a number f individuals are nt fund back. The mistake, hwever, if it has been made by inaccllrate eunting, cannt raise the deathrate, but rathel' lwel's it, s that ne need nt (are abut it any further. Ft' the 3 rd hal'vest series the slice-fd was again l'eversed. The 418 slice-lal'vae f Jar 13 na lnger gt any slices; the 39tl f ja!' A, which had nt had any slices in the nd harvest set'îes, were prvided with them nw. The l'esult f this 3J'd series, with a summar)' f the th ree series tgether is given n page 16

13 ,--1 EXPERMET c. 418 Larvae riginating frm B. Experiment mb. 398 Larvae riginating frm A. Experiment ma. Withut slices. (A) With slices. (B) ' 11 Harvest. Pupae gathered.!deathrate tl Daed, Harvest. Pupae gathered. 'Deathrate tl Dead 1 each 1 i ',-- each 1 1 O.' Dat, L-iV-in-gll: -D-ea-d-.--Ttal. (UPrth'l Laevaa 11. Data i U'ing.,! Dead.[ Ttal.!PuPg.athe- Larvae. 1 st 1 June :11 st 1 June Of ::,' ::: ': : : :,: 11 :,' :: : 3 :: :.: 4th li 4th 5 M th ' 5th th 5 July th 5 July i 9 9,--! ' f 6_-,--_18 8_----,.5_/_'O ,- 4_1 T t_al_ll_n_d Summary Experiment m, V and V. ' Summary Experiment m, V and V. T t_al_a_n_d_a_v_e_ra_g_e_. -'.-! 5. 5 J a_v_e_ra_g_e_.,-_9_4_,--'_11_-,-_1 5--, 1_._4_ /_ --'-- 11 Experiment ma ;--!' Experiment B 7. 5 Of mb V c.--- H c-+_6 '-_18_+_8_ _. +-_4_11 :- i General tta! anti 1' 1:,:' i General ttal and average average. 64, '_' V_-:- 94_c--_ ll _-:-_1O_ 5 --; 1.4 -:---_ 1 _ 1 _ u. Of mutilated in 1 dead pupae

14 18 Here t, the after-effect n th :1 Hl. hanest is again clearly bsel'ved. Prperly speaking, it might be expected tha; this aftereffect shnld be cntillued ill a few harvests mre, as the slicelarvae, aftel' the nil harvest series, lked s much biggel' and mre vigrlls than thse f the dry jal'. As.a matter f fact the lnger 'duratin f the af ter-effect under discussin (in tbis as well as in the previus trial series) elearly finds expl'essin in the eircumstance that the diffel'ellc'es f the deatbrates between the tw trial jars ever increase up t the 4 th harvest. 8, if as a final result it is stated that the mrtalily figllre in tbe slice-jar has fallen by 18.5 l., this figure is certainly nt flattered, but estimated t 1w, a gd deal t lw if ne cnsiders careflllly the figllres and the circllmstances llnder whieb tbey were btained. The sllppsitin mentined n page 11 th at the gnawing f the pupae might be a cnseqllence f the larvae's need f bumidity is crrbrated by cmparing the numbers f dead pnpae mutilated Ol' nt, harvested frm tbe tw jars. Frm tbe table n the frmel' page it is seen th at in the jar withut slices 77 % f the dead pupae were eaten at, and by fal' mst f (hem very strngly, whereas in the slice-jar this figure was nly 1.1) 1 and even then s slig-htl.v that ften dubt arse as t whelhel' r nt they had t be nted dwn as eaten at. Tbc determinatin f the aveeage mrtality amng the eggs, larvae, and pupae was t me f this pl'actical significatin that nee knew tbis, the apprximate quantity f eggs fr a given culture culd be fixed, in rder t ge! at my dispsal a desïl'ed numbet' f beetjes. ''he utlay f t large a number f eggs was a needless labur and waste f time, leaving apart the drawbacks rnnected with it. The labur spent n the {ixing f thesè figul'es in the tit'st three yeal's f experiment, bas been amply rewarded by tbe 'use made f them. The average deathrate f eggs + larvae + pllpae t each 1 eggs Jaid ut amunts t the cnsiderable figure f abut 58 %' L TER A T URE. 1. BREHllL Tierleben. nsekten.. F'REZEL. Ueher Bau und Thätigkeit des Verdauungskanals der Larve des Tenebri mlitr Ber!. Entm. Zeitsch, Bd. XXV Fmsen,.J. L. Beschreibung vn allerlei ns. in Deutschland SALG, TH. Zur Kenntnis der Entwickelung der Keimdrüsen vn Tenebri mlitr. naugural Dissert. Marburg ST URM, JAKOB. Deutsehlands Fauna in Abbildungen uud Beschreibungel1. V. 111sekten. Käfer. Utrecht, Februal'Y 19. KOKLJKE AKADEME VA WETESCHAPPE TE AMSTERDAM. PROCEEDGS VOLUME XX s, and 3. President: Prf. H, A, LORETZ, Secretary: Prf, P. ZEEMA, (Translated frm: Verslag van de gewne vergaderingen der Wis- en atuurkundige Afdeeling, Vls. XXV and XXX). COTETS. ARAUD DEJOV: Sur une prpriété de séries trignmétriques, p.. L. E. J. BROUW EH : Ueber eineindeutige, stetige Transfrmatinen vn Flächen in sich (Siebente Mitteilullg), p. 3. P. GLBERT RAHM: Einwirkung sehr niederer Temperaturen auf die Msfauna. (Cmmunicated by Prf. H. KAMERW:OH OES), p. 35. J. BÖESEKE, W. F. BRADSMA and H. A. J. SCHOUTSSE: The vel city f the diaztisatill reactin a's a cntributin t the prblem f substitutin in the benzene nucleus, p. 49. ' J. J. VA LAAH: On the Critical Quantities f Mercury in Cnnectin with the ncrease f thc Mlecular Attractin n Dissóciatin f the Duble Mlecules.. (Cmmunicated by Prf. H. A LORETZ1, p. 67. J. J. VA LAAR: On the Critical Quantities in the Case f Assciatin, wh en the Mlecular Attractin is Cnsiderablv lncreased n Dissciatin f the Mlecules t the slated Atms, als a in Cnnectin with the Critical Quantities f Mercury. l. (Cmmunicated by Prf. H. A. LORETZ), p. 8. L RATA DHAR, A. K. DATTA and D.. BHATTACHARYA: Catalysis. V. (Cmmunicated by Prf. ERST COHE), p. 99. L RATA DHAR: Catalysis. X. Thermal and phtehemical reaetins. (Cmmunicated by Prf. ERST COHE1, p. 38. L RATA DH AR : Catalysis. X. Explanatin f sme abnrmally large and small temperature cefficients. (Cmmunicated by Prf. ERST COHE', p S. DE BOER: On Fibrillatin f the Heart. (First part). (Cmmunicated by Prf.. K. A. WEHTHEM SALOMOSO), p S. DE BOEH: On Fibrillatin f the Heart. (Part. 11.) On the Relatin between Fibrillatin f the Heart and Gehîiufte Extra-systles. (Cmmunicatcd by Prf.. K. A. WERTHEM SALOMOSO), p.39. LUCE W. SCHUT: Factrs which are f imprtance fr the habit-frmatin f birds. Visual sensatins. (Cmmul1icated by Prf. G. VA RJBERK), p F. M. JAEGER Tw smerie Chlr-Tetracetyl-d-Fructses, p. 34. F. M.JAEGER:On the Crystalfrms f sme Substituted Amides f Para-Tluenesulphnic Acid, p J. F. VA BEMMELE: The elur-markings n thebdy f Lepidptera, cmpared t thse ltheir larvae and pupae, and t thse f their wings, p L. HAMBURGER: On, Centres f Luminescence and Variatins f the Gas Pressure in Spectrum Tubes at Electrical Discharges. (Cmmunicated by Prf. H. A. LORETZ). p G. A. F. MOLEGRAAFF and MAX WEBER :On the Relatin between the Pleistcene Glacial Perid and the Origin f the Sunda Sea <J ava and Suth China-Sea), and its nfluence n the Distributin f Cralreefs and n the Land- and Freshwater Fauna, p (Met twee platen). G. A. F. MOLEGRAAFF: On the Gelgical psitin f the Oil-fields f the Dutch East-ndies, p. 44. M. W. WOERDEMA: On a human vary with a large number f abn r mal fllicles and the genetic significance f this deviatin. (Cmmunicated by Prf. J. BOEKE), p. 448, ' Prceedings Ryal Acad. Amsterdam. Vl. XXll. 15