Various Opinions on Heredity. Ill 



capabilities for performing its particular office in the 

 continuation of the species are wanting or lost, expend 

 themselves in perfecting its own individual system, and 

 hence the animal gradually assumes more or fewer of 

 the secondary sexual characters that belong to the male." 



It is true that, in a few instances, the male has been 

 known to acquire true feminine characteristics, foreign 

 to normal males. Thus, according to Darwin, "char- 

 acteristics properly confined to the female are likewise 

 acquired: the capon takes to sitting on eggs, and will 

 bring up chickens; and what is more curious, the utterly 

 sterile male hybrids from the pheasant and fowl act in 

 the same manner, their delight being to watch when the 

 hen leaves the nest, and to take on themselves the office 

 of a sitter. 



Many male birds normally sit, and hatch the eggs, and 

 there are reasons for believing that the incubating habit 

 was originally shared by both sexes, and I am therefore 

 inclined to attribute such cases as this to reversion to a 

 remote male ancestor, rather than to the acquisition by 

 the male of a female characteristic. 



We may conclude, then, that the transmission by one 

 sex, in a latent condition, of the secondary characteris- 

 tics of the opposite sex, does not compel us to believe in 

 the dual sexual personality of each individual, since we 

 have a much simpler explanation in the view that each ] 

 embryo inherits the power to develop all the characteris- I 

 tics of the species, but that this power does not fully ' 

 manifest itself in the female. 



It may seem difficult to explain in this way the trans- 

 mission by a bull of the good milking qualities of his 

 mother, or the capacity occasionally shown by male 

 mammals of yielding milk, but it is surely simpler to 

 assume that each male inherits, like the females, the 



