RESULTS OF CASTRATION 59 



that the sexual characters of insects are of great lability. 

 Evidently there are in insects other factors besides the sexual 

 glands which control the sexual characters, and even the 

 gonads themselves. We do not know where these factors are 

 localised in the gipsy moth; Goldschmidt is oithe opinion that 

 the male and female factors are present in every cell of the 

 body in given quantities. According to Goldschmidt (1920 a, 

 p. 18) all the characters by which one sex differs from the other 

 are derived from an identical anlage, influenced by a given 

 quantity of the male or female factor. We see that Goldschmidt 

 finds himself forced to make an assumption similar to that 

 which was previously p>ostulated for mammals and birds, i.e., 

 that a neutral soma (asexual or bisexual) becomes monosexual 

 under the influence of a certain internal factor or combination 

 of internal factors at a given time for each species. We shall 

 deal with this most important work of Goldschmidt again in 

 a later chapter (Chapter IX.). In the following section it is 

 shown that in crabs as well as in some insects there are certain 

 external factors which may produce an inversion of the sexual 

 characters from one sex to the other. 



2. The Parasitic Castration of Crabs. 



It has been known for more than thirty years that in certain 

 species of crabs the sexual glands may be destroyed by parasites. 

 This phenomenon has been called "parasitic castration." 

 Giard (1886, 1887) discovered it, and Geoffrey Smith (1906) and 

 Potis studied it exhaustively in Inachus, and in the hermit 

 crab and other species. 



The sexual characters are distinctly pronounced in the 

 Inachus. The male {Figs. 37 and 38) has a longer and a 

 larger claw, and the abdomen, which is relatively small, has 

 only two pairs of appendages, the longer serving for copulation, 

 and the shorter being rudimentary appendages. The claw 

 of the female (Figs. 39 and 40) is shorter and smaller, and on 

 her broad abdomen there are four pairs of fissipedes. The 

 infection of Inachus which results in castration is caused by 

 the Cirrhipedian Sacculina. 



The parasite causes in the male Inachus a reduction of the 

 copulatory appendages which are a very pronounced male 

 sexual character, and the assumption of female characteristics 



