DEVELOPMENT OP THE EXTERNAL ORGANS OF GENERATION. 951 



more nearly its original character, and may have a wide external opening 

 beneath the root of the penis, so as to resemble the female vagina, whilst 

 the penis is itself destitute of any trace of the urethral canal ; in some of 

 these cases, again, the testes have not descended into the scrotum ; whilst 

 the absence of beard, the shrillness of the voice, and the fulness of the 

 mammie, have contributed to impart a feminine character to these individ- 

 uals, their male attributes, however, being determined by the seminiferous 

 character of the essential organs, the testes. 1 In the female organs, on the 

 other hand, a greater or less degree of resemblance to those of the male 

 may be produced by the enlargement of the clitoris, by its furrowing or 

 complete perforation by the urethra, by the closure of the entrance of the 

 vagina and the cohesion of the labia, so as to present a likeness to the un- 

 fissured perineum and scrotum of the male, by the descent of the ovaries 

 through the inguinal ring into the position of the male testes, and by the 

 imperfect development of the uterus and mammse; with these abnormali- 

 ties are usually associated roughness of the voice and growth of hair on 

 the chin, and a psychical character more or less virile. True Hermaph- 

 rodisrn, in which there is an absolute combination of the essential male and 

 female organs in the same individual, is comparatively rare. It may occur 

 under the forms of lateral hermaphrodism, in which there is a genuine ovary 

 on one side and a testis on the other, in which case the external organs are 

 usually those of a hypospadic male; transverse hermaphrodism, in which 

 the external and internal organs do not correspond, the former being male 

 and the latter female, or vice versa; and double or vertical hermaphrodism, 

 in which the proper organs characteristic of one sex have existed, with the 

 addition of some of those of the other: this is the rarest of all, and it is 

 not certain that the coexistence of testes and ovaria on the same side has 

 ever been observed in the Human species. 2 



791. We have now to follow the course of the development of the princi- 

 pal organs of Animal life ; and shall first notice that of the Skeleton? The 



FIG. 352. 



Transverse section through the Embryo of the Chick at the close of the first day of incubation, mag- 

 nified about 100 diameters, ch, chorda dorsaiis ; h, external serous or corneal layer ; m, medullary por- 

 tion of serous layer; Pv, primitive groove between the dorsal laminae J?/and m; dd. intestinal epithe- 

 lial or glandular layer (mucous layer) ; iiwp, prevertebral mass, in which the primary or protovertebrse 

 are formed, and which is continuous with the middle lamina, xp ; inch, fissure in the middle lamina, 

 presenting the first indication of the pi euro-peritoneal cavity, aud of the subsequent division of the 

 middle lamina into two layers. 



first differentiation of parts that occurs in the middle lamina of the blas- 

 todermic vesicle (Fig. 352), is the formation of a solid cartilaginous rod, 

 termed the uotochord or chorda dorsaiis (ch), which extends throughout the 

 whole length of the future vertebral column, and along the base of the 



1 The vesicula prostatica has presented an unusual development in some of these 

 cases; see Prof. Weber (Inc. cit.), and Prof. Theile's Account of a Case of Hy|><>- 

 spadias, in Muller's Arohiv, 1847. 



2 On this subject, see Prof. Simpson's Article Hermaphrodism in the Cyclop, uf 

 Anat. and Phys , vol. ii. 



3 See Balfoiir, Studies from the Physiol. Lab of Cambridge, PI I. 



