NOTES AND LITERATURE 



RUSSO ON SEX-DETERMINATION AND ARTIFICIAL 

 MODIFICATION OF THE MEND ELI AN RATIOS 



In the April number of the Naturalist Professor Jordan 

 presents an interesting review of recent literature on sex-deter- 

 mination in the course of which he gives an extended account 

 of RussoV experiments with lecithin-fed rabbits. Great impor- 

 tance is attached to tins work because it points to conclusions 

 diametrically opposed to those reached within the last ten years 

 by nearly every one else who has studied sex-determination either 

 from the standpoint of the cytologist or from that of the experi- 

 mental breeder. The nearly unanimous verdict has been that 

 sex-determination is a matter of gametic differentiation, and that 

 the sex of a developing organism is not influenced by conditions 

 of nutrition either applied to it directly or brought to bear upon 

 the mother. The only exception, apparent but not real, as I 

 pointed out in 1903, 2 is afforded by organisms in which both 

 parthenogenesis and sexual reproduction occur. Abundant nutri- 

 tion favors parthenogenesis, scanty nutrition causes a return to 

 sexual reproduction, including the production of males. Russo 

 has revived the older idea that in non-parthenogenetic organisms 

 also scanty nutrition is a cause of male-production. If true, 

 this is a matter of the greatest importance, both theoretical and 

 practical. Jordan is quite right in so regarding it, but has 

 apparently failed to appreciate the uncritical character of 

 Russo 's evidence. This has, however, already been pointed out 

 by several writers, most recently by Punnett, 3 whose brief but 

 convincing paper seems not to have been seen by Jordan. 

 Russo himself has never published the results of his experi- 

 ments as a whole, but only of sdn hd < xp< riiix h ts the results of 

 which were favorable to his thesis. This fact alone would throw 

 Russo 's claim out of an impartial court, but to be more than 

 fair to Russo, it may be said that his experiments have been 



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