386 Experimental Zoology 



more young in a litter than the poorly nourished. Putting to- 

 gether all those cases where more than nine young were present 

 in a litter, which indicates favorable parental conditions, there 

 were produced 49 females and 43 males. Where fewer than 

 9 were born there were 62 females and 71 males. Although 

 there is a slight excess of females in the former and of males in 

 the latter cases, the numbers are so nearly equal that the influ- 

 ence of nutrition cannot be said to be apparent. It may be 

 noted that when more young are present the conditions for 

 each are poorer, yet, in fact, more females were born. 



Schultze has carried out some experiments with white mice. 

 One lot was starved. They were long in reaching maturity, 

 and weighed only a half to a third as much as well-fed mice. 

 This lot produced 4 males and 4 females. Another lot pro- 

 duced 42 males and 48 females. Clearly there was no effect of 

 nourishment to be seen. Schultze also examined the product 

 of the second generation of starved mice, some of which were 

 also starved and others fed. He obtained 36 males and 43 

 females for the starved ones, and 20 males and 28 females for 

 the well-fed individuals. He also paired poorly fed males with 

 well-fed females in order to see if, as has been claimed, the better- 

 fed parent would determine the sex. Well-fed females paired 

 with well-nourished males gave 46 males and 36 females. The 

 same females were then paired with poorly nourished males and 

 gave 38 males and 37 females. Again there is no evidence of the 

 sex being determined by the condition of the parent. 



Schultze also tried the effects of feeding mice on foods that 

 were rich or poor in albumen. Potatoes and bacon were used 

 as having little albumen, but on this diet the animals did not 

 reach sexual maturity. Fed on white bread and water, they gave 

 18 males and 22 females. For a food rich in albumen, tropon * 

 was used, also other food rich in albumen, along with salt and 

 milk. There were produced 29 males and 26 females. 



These experiments go far toward establishing the view that 



tropon contains 21 per cent albumen, 60 per cent carbohydrates, and 15 

 per cent fat. 



