TABOO AND GENETICS 45 



gametic for sex — i.e., the sperm instead of the 

 eggs is uniform as to the sex chromosome. 



Insects are (in some cases at least) hke birds 

 as to the odd chromosone — the opposite of 

 man. But as to secondary sex-characters they 

 differ from both. These characters do not 

 depend upon any condition of the sex organs, 

 but are determined directly by the chemical 

 factors which determine sex itself. (20.) 



In Crustacea, the male is an inhibited female 

 (the exact opposite of birds), as shown by the 

 experiments of Giard and Geoffrey Smith on 

 crabs. A parasite, Sacculina negleda, some- 

 times drives root-like growths into the spider 

 crab, causing slow castration. The females thus 

 desexed do not assume the male type of body, 

 but castrated males vary so far toward the 

 female type that some lay eggs (3, p. 143 ; 20). 

 It is the discovery of such distinctions which 

 makes it necessary to re-examine all the older 

 biological evidence on the sex problem, and to 

 discard most of it as insufficiently exact. 



The work of Steinach (12, pp. 225f.) on rats 

 is another well-known example of changing sex 

 characters by surgery. Steinach found that an 

 ovary transplanted into a male body changed 

 its characteristics and instincts into the female 

 type. The growth of the male sex organs he 

 found to be definitely inhibited by the ovaries. 

 He went so far as to transplant the whole 



