190 bulletin: museum of comparative zoology. 



II. Sex an Attribute of each Gamete, and Hereditary. 



The last forty years have seen the rise, cuhui nation, and at least 

 incipient decline of a plausible but fundamentally erroneous idea about 

 sex, — the idea that it is subject to control through the environment of 

 the developing organism. The latest manifestation of this idea is found 

 in Schenk's (:02, :02'' ) theory of sex-control in man through regulation 

 of the nutrition of the mother. One or the otlier, or both, of two fal- 

 lacies are involved in all such theories of sex-control. (1) It is known 

 that in animals which reproduce sometimes by parthenogenesis, some- 

 times by fertilized eggs, good nutrition favors the former process, poor 

 nutrition the latter. But in the former process, when it proceeds with- 

 out interruption, the offspring arc all of the female sex, whereas the 

 lirst eftect of poor nutrition is the production of mak's, and tliis is fol- 

 lowed by the production of fertilized eggs. The conclusion is drawn 

 that good nutrition favors the production of females among animals gen- 

 eraliy, and that poor nutrition results in general in tlie production of 

 males. As a matter of fact the primary effect of good nutrition, in the 

 case described, is not female production, hut ixtrthenogenesis, and the 

 effect of poor nutrition is, not jiTiniarily male production, but reproduction 

 bi/ fertilized eggs, in wliicli process the production of males is necessarily 

 involved. The determination of parthenogenesis instead of sexual re- 

 production is one thing, determination of sex in animals not parthe- 

 nogenetic is quite another thing. (2) The other fallacy mentioned 

 relates solely to the case of animals not parthenogenetic. Its true 

 nature has been repeatedly pointed out, but apparently none too often, 

 for Schenk seems to rest his theory upon it. Feeding experiments, 

 especially with Lepiiloptera, often lead to the production of an excess of 

 males when tlie nutrition is scanty, simply because the female requires 

 a greater amount of food to complete her development. Excess of males 

 because of a greater mortality among female individuals is wrongly 

 interpreted as a production of male individuals by a scanty diet. 



On the other hand, evidence has been steadily accumulating in recent 

 years to show that sex is inherent in the germ, and is not subject to 

 control in the slightest degree by environment. A masterly summary 

 of this evidence has been made in the case of animals by Cucnot ('99), 

 and in the case of plants by Strasburger (:00). 



If it be true that sex is inherent in the germ, and is independent of 

 environment, it must be contained in one or the other or both of the 



