Oa the Life-Hìstory and Development of the Genus Myzostoma. 575 



seems to be a male, but at the anterior end of the right testis there is a 

 pig-mented fold which possesses a uumber of button-lìke processes, 

 and on microscopie examination it is seen that these processes are ova, 

 which there He close to the surface, and are further scattered between 

 the lobules throughout the whole testis. The MUllerian duct is also 

 very well developed. 



He found in another individuai [D) an ovary on the left side with 

 normal eggs, which however show in great part traces of degeneration. 

 On the right side the sexual organ has chiefly the characters of a testis. 

 The sexual ducts are those of a female. 



Thus it is seen that in the Amphibia hermaphroditism is brought 

 about by the conversion in some individuai of part of its male sexual 

 cells into ova, or of its female cells, if it be a female into spermatozoa, 

 and is not really due to the rudiment of a hermaphrodite state present in 

 ali individuals. Further the so-called rudimentary ovary is not con- 

 cerned in the production of hermaphroditism. 



Some interesting researches bave recently been published by von 

 Brunn ^ on the spermatozoa of Paludina vivipara. In this paper the 

 author explains the origin of the worm-like spermatozoa by the hypo- 

 thesis 2, that there is a tendency in the sexual characters of the male 

 organs of Paludina vivipara to produce female characters, and compa- 

 res very justly the structure of the testis of Paludina to the hermaphro- 

 dite gland of the Pulmonata. He points out that the worm-like sper- 

 matozoa occupy the same position in the testes oi Paludina as the ova 

 in the hermaphrodite gland of Pulmonata. He further considers ^ the 

 Pulmonate hermaphrodite gland to be derived from a simpler unisexual 

 state*. 



From ali this I think we may gather that at any rate in very many 

 cases hermaphroditism is a secondary condition brought about in the 

 males or females , or in both , of unisexual animals , either by some 

 innate tendency to it or by something in the conditions of existence of 

 the particular species. 



It was pointed out further back that among Crustacea and A7ine- 



1 Max v. Brunn, Untersuch, über die doppelte Form d. Samenkörper von 

 Paludina vivijiara. Archiv f. Mikrosk. Anat. Bd. 23. Heft 4. 



- »Weibliche Tendenz im Hoden.« 



3 1. c. Physiologischer Theil. p. 478. 



* It is worthy of remark that one often finds in the vesiculae seminales of 

 the male of M. glahrum , not small quantities of undeveloped spermatozoa. One 

 might perhaps here in the male assume the existence of a »weibliche Tendenz im 

 Hoden«. 



