DEVELOPMEN1 V\I> DURATION OF LIFE IN INSKi DS. 9 



short prolongation of the larval stage. Analogous experiments 

 \\ere afterward- made by Kellogg and Bell ('04 a and b). Pictet 

 ('05) came to the convirtir.n that the larval stage is prolonged 

 and the pup.il -tage shortened by feeding caterpillars on plant- 

 containing few food -stuffs, but that the conjoint periods of 

 development do not undergo any changes. A prolongation of 

 larval lift- cau-ed by inadequate food was lately determined by 

 Northrop Ci~) Tangl. ('090), finally, maintains that the lar\a- 

 of flies reared on pure egg-white which they refused to take 

 underwent transformation approximately a week later than 

 normally. These results are, in general, concordant with my 

 observations on starved caterpillars. On the other hand, the 

 ob-ervation- of Krizcnecky ('14) and of Szwajsowna ('i< on 

 the larva- of Tenebrio molitor which underwent metamorphi>-i- 

 earlier \vhen totally starved contradict the above determination-. 

 A -imilar discrepancy may also be remarked in analog .u- inve-n- 

 .uations on amphibians. While B.irfurth (87) and others ha\ 

 'rtained that starvation of amphibians causes an eleration of 

 i heir metamorphosis, other investigators induced retardation 

 ot ihe-e processes by the administration of poor food to tadpole-. 

 It has been emphasized by Wolterstorff ('96), Morgan '07 .Kauf- 

 man ('18) and others that in amphibians the influence probably 

 ilillers in different developmental stages of the tadpole- u-ed f. ir 

 -tarvation. The former of the above mentioned in\ e-ti-ai..i ~ 

 ill pri\'ed large tadj)oles of food, in part shortly before their 

 transformation, while the others used far younger -pecimen-. 

 SimilarK' the experiments of Kellner and the follouin- aiithm- 

 and also my own were made on youni; caterpillar^ \\hile the 

 ob-er\ations of Krizenecky anil of .s/\\aj-i '.\\iia refer to older 

 lar\a-. In another experimental -tudy on -tar\-d tadpole- 

 l\"|)ec, 22d and b) I sin ceedcd in confirming the abo\ c \ ie\vs of 

 \\ I'lier-torll. Morgan and other-. My experiment- -h<>\\e<l that 

 metamorphosis of the tadpole- to \\hich -tarxation w.is applied 

 before the fiftieth day of their development undergoes retarda- 

 tion, where as (transformation i- accelerated when tadpole- are 

 -tarvedafter the-i\ty fifth day of their life. In t hi- -tudy on cater- 

 pillars similar behavior was al-o noted in one and the same ma- 

 terial of female larva-. It turned out that the caterpillars to 

 which total starvation ha- been applied approximately since 



