Note on Russo’s attempt to show differentiation, etc. 609 
Note on Russo’s attempt to show differentiation of sex in the 
ovarian ova of the Rabbit. By Walter Heape, M.A., F.R.S., 
Trinity College. 
[Read 26 October 1908.] 
The question as to whether or not the conditions of environ- 
ment exert influence on the proportion of the sexes produced by 
an animal is a matter of great interest. I am myself strongly of 
opinion such is the case and that physical conditions and food 
especially, that is to say the quality or quantity of food supplied 
to the mother and her individual capacity for assimilating food 
and transmitting nutriment to the ovary under varying conditions 
of metabolism, are factors of importance in determining the pro- 
portion of the sexes ultimately produced by all animals in which 
only a limited number of their ovarian ova come to maturity. 
I have dealt with this matter somewhat fully in a forthcoming 
paper on “ the proportion of the sexes amongst whites and 
coloured people in Cuba”; I would only here add that histo- 
logical examination supports this view and that it would appear 
to have a very important bearing, not only on sex ratio but on 
many other problems concerned with the proportionate production 
of individuals carrying a variety of other characters. 
On the assumption that the female germ cell is possessed of 
dominant sexuality, it would be of extreme value to discover 
means by which ovarian ova can be histologically recognised as 
M. or F. ova. 
For this reason the publication of elaborate investigations on 
the subject by Russo 1 is calculated to excite considerable interest, 
for he thereby seeks to show: (1) that by means of the introduc- 
tion of lecithin into the doe rabbit he can profoundly modify the 
proportion of the sexes produced by her; (2) that he can thereby 
also demonstrate histologically two kinds of ovarian ova, the one 
of which he declares to be M. the other F. ova. 
So far as the former is concerned, an examination of the tables 
published by Russo has led my friend Professor Bateson to con- 
clude they are not of statistical value, inasmuch as it would 
appear the cases recorded are selected cases and do not include all 
births 2 . 
1 Russo, “ Modificazioni sperimentali dell’ elemento epitheliale dell’ ovaia dei 
mammiferi,” Atti R. accacl. Lincei, Roma, vol. xvi. 1907; “ Metodi adoperati per 
aumentarc artificialmente la produzione del sesso femminile nei conigli,” etc. 
Rend. d. R. accad. Lincei, Roma, vol. xvi. 1907; “Sulla origiue e sulla fuuzione dell’ 
apparato mitoeondriale nelle cellule sessuali dei mammiferi,” 1’roc. acad. Gioenia, 
Sci. Nat. Catania, 1908. 
2 Bateson, “Heredity of sex,” Science, No. 698, vol. xxvii. 1908. 
