INBREEDING AND SELECTION IN DROSOPHILA AMPELOPHILA 141 
SEX-RATIO AND SELECTION 
1. Introductory 
The once rather generally accepted notion that nutrition was 
an influential factor in the control of sex, based on the experiments 
of Yung (’85), Born (’81), and others, has given place to the now 
as commonly accepted idea that sex is determined prior to or 
at the time of fertilization and is independent of the food. The 
experimental work of Cuénot (’99) King (’07) and others, and the 
splendid cytological researches of Wilson and his students are 
largely responsible for this change of view and have been so fre- 
quently reviewed in the various recent discussions of the problem 
of sex that they need not be further detailed here. 
The writer tried some starvation experiments on Drosophila 
in 1904. During the past year more extensive experiments were 
carried on under his direction by Mr. Claude D. Holmes, on the 
effects of starvation during successive generations upon the sex- 
ratio. These are published under a separate title(’10). It will 
suffice in this connection, to state that the results coincide with 
those of recent workers, namely that nutrition does not affect the 
sex-ratio. 
2. The normal sex-ratio 
One fact was very apparent in these earlier tests and in all sub- 
sequent experiments, that, under the varying conditions in these 
creatures were reared, there was the same persistance of the pre- 
dominance of females over males. Below (table 7) is given the 
TABLE 7 
roo pou | RE | ue fan aan 
IB aITAN as Ae pee seed etka ee eciers 10506 4972 5534 1:1.113 
GRADES cpm s . teen eee oe 2161 995 1166 1S fe Bria 
Tomatoes and grapes...... 4048 1948 2105 1:1.083 
IGTATAS Ge ce. A arches 10218 4757 5461 1:1.14 
MOT AME Jeo eB. edo pelts 26933 12667 14266 1:1.126 
