414 William Morton Wheeler 



mal experience in the testes of many animals. In sand-hoppers 

 (Orchestia) to quote a well-known case (and there are many others 

 in the Crustacea) spermatozoa are produced in the anterior part 

 of the young testis while posteriorly the whole space is occupied 

 by two or three large ova i^ide Boulenger '08). 



"The particular interest of the phenomenon in this case is its 

 association with a definite cause, that is, parasitism. We are also 

 able to come to some conclusion as to the degree in which such a 

 condition can be called true hermaphroditism. Some striking 

 evidence is offered by spider crabs which were once infected by 

 Sacculina but which have outlived their parasite and recovered 

 from its influence. Such crabs occur in nature in fair frequency 

 and the only reminder of their former condition is the chitinous 

 ring on the abdomen which surrounded the peduncle of the para- 

 site. After the death of the external part of the Sacculina the root 

 system may continue to exist in the host and it is only when this 

 has disintegrated and been absorbed that regeneration of the 

 gonads becomes rapid, for the still living roots repress the devel- 

 opment of the sexual organs as effectually as the living parasite. 

 A few crabs however were found in which the gonads had again 

 attained full size and maturity. One was a female with a well- 

 developed ovary and four were males only shghtly modified ex- 

 ternally, with glands producing large quantities of spermatozoa. 

 The remaining four cases were remarkable for the crabs showed 

 with a complete external hermaphroditism the corresponding 

 gonads. In all four animals the reproductive gland consisted of a 

 male part with ripe spermatozoa, and a female division with large 

 pigmented ova. The ducts were usually absent, but one individ- 

 ual possesssed both vasa deferentia and oviducts. The sequel to 

 these observations is given by the experimental evidence which 

 Smith then obtained. It was attempted to destroy the parasite 

 by removing the external part and the crabs so freed were kept 

 under comfortable conditions for several months and the few 

 survivors then killed. Regeneration had obviously occurred to a 

 considerable extent, but the gonads were nearly always unisexual. 

 In one individual alone, which was externally a hermaphrodite 

 there was a gonad similar to those just described. In spite of the 



