FARTHER DEVELOPMENT OF THE EXTERNAL ORGANS. 825 



into the urogenital sinus. Within the vestibule, which is the shortened but 

 ■widened remains of the urogenital sinus, the urethral orifice is seen, the lu'ethra 

 itself undergoing considerable elongation. 



In tlie male, on the contrary, the j;c'«w continues to enlarge, and the margins 

 of the groove along its under surface gradually unite from the primitive urethral 

 orifice behind, as far forwards as the glans, so as to comiilete the long canal of 

 the male itrcthra, which is therefore a prolongation of the urogenital sinus. This 

 is accomplished about the fifteenth week. "When this union remains incomplete, 

 the abnormal condition named iLUpo.^padlas is produced. In the meantime the 

 prcjniec is formed, and, moreover, tlie lateral cutaneous folds also unite from 

 behind forwards, along the middle line or raphe, and thus complete the scrotum, 

 into which the testicles descend in the course of the eighth month of fojtal life. 



The corpora cavernosa, which are at first separate, become united in their 

 distal portions in botli sexes ; but the corpus spongiosum lu'ethraj which is 

 also originally divided in all embryoes, and in the female remains so in the 

 greater part of its extent, becomes enlarged in the male in the glans penis, and 

 its two parts united mesially both above and below the urethra, so as to enclose 

 the whole of that tube from the bulb forwards to the glans. 



TYPE OF DEVELOPMENT AND ABNORMAL FORMS OF THE GENITAL 



ORGANS. 



The type of development of the genital organs may be stated to differ in the 

 several parts of the system in the two sexes as follows, viz. : — 



1st. It is single and homological in the external organs. 



2nd. It is double and heterological in the middle organs or passages. 



3rd. It is partially double and heterological in the productive organs. 



Accordingly the congenital malformations of the reproductive organs admit of 

 being distributed under the following divisions : — 



1st. Abnormal forms attributable to deficient, redundant, or abnormal modes of 

 development of one or more of the external organs in either sex, producing an 

 approach to tlie fonn of the otlier sex. 



2nd. Forms referrible to deficient, redundant, or abnonnal modes of develop- 

 ment of one or other of the two sets of sexual passages, viz., of the Wolffian or 

 Miillerian ducts, so as to lead to the greater or less predominance of sexual 

 characters in a part or the whole of these passages inconsistent with tliose pre- 

 vailing in other parts of the system, or to the coexistence of both sets of pas- 

 sages in whole or in i:)art. 



8rd. Extremely rare forms referrible to the possible coexistence of the produc- 

 tive parts of testicles and ovaries in the same individual, usually combined with 

 more or less of the foregomg kinds of malformation. 



Upon the subject of these malformations the reader may consult the learned 

 and able article Hermaphroditism by Sir James Y. Simpson in tlie Cyclop, of 

 An at. and Physiol. 



Upon the subject of malformations in general the following works are recom- 

 mended, viz. : — 



Isid. Geoff. St. Hilaire, Hist. Gen. et Partic. des Anomalies de I'Organisa- 

 tion, &c., 3 torn. Paris, 1832 — 6 ; Cruveilhier, Anat. Pathol., &c., Paris, 1S;>() — 42. 

 Otto, Sexcentorum Monstrorum desc Anat. Vratisl., 1841 ; Th. L. W. Bischoff. 

 Uber Missbildungen, &c., in R. Wagner's Handworterbuch der Physiol., 1843 ; 

 Wm. Vrolik, Tab. ad illustr. Embryol. Hom. et Mammal, tam Natiu-. quam Abnor- 

 mem, Amstel., 1849, and tlie article " Teratology"' by the same author in Todd's 

 Cyclop, of Anat. and Physiol. ; Aug. Forster, Die Missbildungen des Menschen. &c., 

 Jena, 1861 ; as also the systematic works of Rokitanski and others on Patho- 

 logical Anatomy. 



The following tabular scheme of the Coreesponding Parts of the 

 ffenito-urinary organs in the two sexes, and of their relation to the 

 Formative Rudiments of the common embryonic type, may be useful in 



