40 J. PERCY BAUMBERGER 



begin till the females were seven to twelve days old (normal pe- 

 riod thirty-six hours) and the number of eggs was 117instead of 

 the normal 576 (24 per day). Only five larvae emerged, 49 em- 

 bryos died owing to deficiency of the sperm, and 63 eggs were 

 unfertilized. Anatomical examination b}^ the author ('13 e) 

 showed that only 20 to 40 eggs are normally formed in the body 

 of the female at the time of emergence from the pupa. These 

 are deposited in forty-eight hours, and after that all the stored 

 material in the eggs, normally 24 per day, must be derived from 

 the body and food of the insect. The effect of the food of the 

 adult upon fecundity is very marked, thus 'non-fertile' sister 

 adults from potato-fed larvae were placed, 1) on potato, where 

 they laid one egg per day for 7 to 13 days and, 2) on potato and 

 yeast, where they laid 10 to 15 eggs per day after 5 days and then 

 24 eggs per day. The converse experiment was to place sister 

 adults raised from larvae fed on potato and yeast on 1) potato 

 and yeast, where after 24 hours, 20 to 27 eggs per days were de- 

 posited for 10 to 17 days and, 2) on potato, where after 24 hours 

 20 to 27 eggs were deposited for 3 days and after that but 1 egg 

 per day. These experiments all account for the death in the 

 embryonic stage of eggs of a normal female, but the following ex- 

 periment shows clearly that it is due to resorption by the female 

 of the sperm cells in the bursa copulatrix (Guyenot, '13 b). 1) 

 Adults from larvae reared on potato when placed on yeast laid 

 from the 4th to 15th day 300 normal eggs, on potato after 7 to 13 

 days, 2 to 3 fertile eggs, later 20 eggs which died without hatching 

 although fertihzed, and finally 30 unfertihzed eggs. 2) Adults 

 from larvae raised on yeast, when placed on yeast deposited 24 

 eggs per day after 36 hours, and on potato, behaved the same as 

 adult bred on potato, but the effect was slightly postponed. 



The foregoing considerations show that the fertility of adults 

 is a question of gross nutritional requirement and that it is diffi- 

 cult to interpret the yeast requirement in these cases, as a need of 

 special substances. This is especially true since the accessory 

 factors or vitamines which have been studied by Funk ('11), Os- 

 borne and Mendel ('13), Hopkins ('12), and others are necessary 

 only in extremely minute quantities and are not used up in a 



