DEVELOPMENT! A\l> DURATION O LIFE IN [NSE< FS. II 



in time. The prolongation of the larval period in younger cater- 

 pillars starved before tin- -cventh day after the last moult m.iy be 

 .])!; lined, on the contrary, by impeded secretoric function of tin- 

 brain or by certain anomalies of its activity in starved organism-. 

 If the pro sses occurring in the pupa were a continuation of 

 i hose Liking pi, ice in the caterpillar and leading to pup.it ion, 

 the abbreviation of the pupal stage in starved specimen- could 

 noi In- reconciled with the above explanation. But these proc- 



- dilfi-r not only energetically as it has been shown by Tangl 



The processes of pupation may morphologically be 



reduced to the hi-tolysis of almost all larval tissues into a'homo- 



eous mass \\hich fills up the pupal body, whereas the trans- 

 loniiation of the pupa into the fully-developed insect con-i-t- 

 in the de\ elopcinnt of the so-called imaginal discs, i.e., of small 



1 1 in n la t ions of cells. In my present experiments < -cries B) 

 I -ucceeded moreover in establishing certain physiological char- 

 acters which point to another difference. In series M the cater- 

 pillars \\ere deprived of food every second day for -?o days after 

 their hatching from eggs, i.e., at a time when there .ire not e\ni 

 any traces of histolytic processes in the larval body. From the 

 twenty-first day till the end of the larval period the animals \\ en- 

 led every day and underwent the normal number of moiilt>. 

 From the appertaining items on Tables II. and III. we see that 

 tlu- caterpillars belonging to this series not only remarkably 

 dcla\cd the term of their pupation, but also that the duration 

 of the pupal stage was considerably shortened. Thi> .ibbn -\ia- 

 tion amounted in the average of broods to 17.4 per cent, of the 

 average duration of life of normal pupae in male- and t" JJ.S per 

 cent, in lenialc-. Consequently, the evolutive processes charac- 

 teristic o! t In- pupa are not a continuation of i ln.-e c li.m^e- \\ Inch 

 are ( -hara< tei i/cd by llistolysis ( ,f larxal ti-su r -. \\ V -t-i- that by 

 temporarily slarxin^ \oun- caterpillars ^cric- /> u ( nia\' segre- 

 gate these pro- . <- am I |>ro\e that processes of the development 

 ot the imaginal discs may bci;m far earlier, i.e., XKHI after the 

 hatching of the caterpillar from the e^- It "u-ht therefore to be 

 interred that the brain has t \\o ^eparate functions in normal Con- 

 ditions, (I) it cause- In-loly-i- of l.ir\al tisSUCS, J it delaN'- | he 

 evolution of imaginal di-c-. Muring inanition of i .lU'rpillars the 

 inlluence of the brain hindering the development of iniagin.il discs 



