HERMAPHRODITISM. 63 



theories of what we now call the homology of the reproductive organs 

 and ducts in the two sexes. Through the labors of the anatomists of 

 Cuvier's school, such as his fellow-worker Geoffroy St. Hilaire, and 

 yet more through more recent embryological discoveries, there is now 

 both clearness and certainty as to the main facts. The reproductive 

 organs proper, the ducts, and the external parts, are developed upon 

 the same plan in male and female. Thus, except in the lowest verte- 

 brates, what serves as an oviduct in the female is equally present in 

 the embryo male, and persists in the adult as a more or less function- 

 less rudiment. In the same way, what serves as the duct for the 

 sperms (vas deferens) in the male, is equally present in the embryo 

 female, and persists in the adult as a rudiment, or is diverted to some 

 other purpose. This is a perfectly normal occurrence, dependent 

 upon the embryological history of the ducts in question. It is neces- 

 sary, however, to realize both the primitive resemblance and the 

 fundamental unity of the two sets of organs, in order to understand 

 how partial hermaphroditism is so frequent, and also to distinguish 

 it from "spurious hermaphroditism," where a merely superficial 

 abnormality or even injury of the ducts in one sex produces a 

 resemblance to those of the other. 



We have already mentioned that in the case of twin calves two 

 females may occur, and both are then normal; or two normal twin 

 calves may be born of opposite sexes; but in the third place, if both be 

 males, one of these very generally exhibits the peculiar phenomena of 

 what is called a "free-martin." In the commonest form of this, 

 partial hermaphroditism is well illustrated. The essential organs are 

 male, but there is a rudimentary uterus and vagina, and the external 

 organs are further those of a female. 



It is necessary to note that a simulation of even this partial 

 hermaphroditism may result from malformation or rudimentary 

 development of the external organs. On this subject we may quote 

 an acknowledged authority, alike in anatomical and embryological 

 matters. "From the fact," Prof. O. Hertwig remarks, "that the 

 external sexual organs are originally of uniform structure in the two 

 sexes, we can understand the fact that, in a disturbance of the normal 

 development, forms arise in which it is extremely difficult to decide 

 whether we have to deal with male or female external organs. These 

 cases, in earlier times, were falsely interpreted as hermaphroditism. 

 They may have a double origin. Either they are referable to the fact 

 that in the female sex the development may proceed along the same 

 path as in the male, or to this, that in the male the normal develop- 

 ment may come at an early stage to a standstill, and lead to the 

 formation of structures which resemble the female parts." In the first 



