PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 435 



male gonad composed of. cells characteristic of the male complex of 

 chromosomes. Parasitized females show no assumption of male pig- 

 mentation nor do they change in size. 



Relation of the Testes to Sex Characters in Crustaceans. Among 

 the Crustacea the relation between the testes and sexual characters is quite 

 pronounced. According to Potts (a) (&), Smith and others, certain male 

 crabs which have become parasitized by other crustaceans, develop the sec- 

 ondary sexual characters of the opposite sex. The parasite after attaching 

 itself develops in a manner which brings about partial or complete destruc- 

 tion of the reproductive tissue of the host. The males so infested show every 

 degree of modification toward the female type; the legs are small, the 

 stylets reduced, the abdomen broad, and typical biramous appendages 

 appear. Infested females, on the contrary, although their ovaries are 

 destroyed, undergo no change toward the male type, although the ab- 

 dominal appendages are somewhat reduced. Inasmuch as the testes of 

 the male suppress the development of the secondary sexual characters that 

 ordinarily appear only in the female, there is, in these crabs, a relationship 

 between the generative tissue and the sexual characters. 



Relation of the Testes to Sex Characters in Birds. In birds the rela- 

 tionship between the gonads and plumage is apparently the reverse of the 

 relationship described 'above in the crab. Female fowls and pheasants 

 often assume, in their old age, the characteristics of the male. Similar 

 alterations occur as the result of diseased ovaries. The removal of the 

 ovaries of young chicks and ducks also permits of the development of 

 secondary sexual plumage like that of the male. Also, castration of the 

 Seabright cock, the plumage of which is like that of the female, results 

 in plumage like that of the ordinary male fowl. The plumage of cocks 

 does not appear to be altered by castration ; the combs, spurs and wattles, 

 however, are less highly developed (Goodale, Boring and Morgan, 

 Walker). Therefore, it may be argued that the female possesses the 

 potential ability to assume full male plumage, but does not do so in the 

 presence of a normally functioning ovary; hence, the ovary in some way 

 inhibits or prevents the establishment of certain sexual characteristics 

 which appear normally in the male. However, Goodale has shown that 

 different parts of the soma react differently to the influence of the gonads 

 that is, some characters such as size in females, voice, mandible color in 

 ducks, and certain phases of behavior, are independent of either ovary or 

 testis, while others depend entirely or to some extent upon the proper 

 functioning of the gonads. For instance, the comb, wattles, fat dis- 

 position, size in males, summer plumage, and some instincts in ducks are 

 influenced by the testis, while plumage, form, color, and some phases of 

 behavior are influenced by the ovary. Therefore, the secondary sexual 

 characters in birds are not equally affected by the primary sex organs. 



Relation of the Testes to Sex Characters in the Triton. Further evi- 



