Experiments to Modify the Sex Ratio in Toads. 87 
If our assumptions are correct, the above formula ought to rep- 
resent adequately our growth curves. It was shown that the above 
formula can be transformed into the following forms as particu- 
lar cases: 
y = a + 6 log (x + c) 9 
and y = a + bx + c log x. 
These are formulas which are already extensively used for 
graduating observed growth curves. Thus there is no further 
need to test the adequacy of the formula to represent the growth 
curves, since numerous applications have been made with satis- 
faction and already published by various investigators. I there- 
fore put forward the following provisional definition of growth 
considered as a process: "An organism tends during growth to 
form greatest amount of mass with least loss of growth capacity." 
Further the present investigation furnishes a biological meaning 
to the logarithmic formulas which have been extensively used 
without appreciating the full significance of their properties. 
The cases of abnormal growth were also discussed but will be 
treated more fully in a future publication. 
52 (577) 
Experiments to modify the sex ratio in the toad. 
By HELEN DEAN KING. 
[From the Wistar Institute of Anatomy and Biology.] 
Several series of experiments were made in the spring of 19 10 
in order to ascertain whether the sex ratio in the toad can be 
altered by subjecting the eggs to different environmental condi- 
tions at or before the fertilization period. 
Lots of eggs fertilized in various solutions of alcohol (.13 
per cent, to 2 per cent.), as well as those fertilized with sperm from 
