392 HISTORY OF THE HUMAN BODY 



sions several compensatory changes, such as the lengthening 

 of the ovarian nerves and blood-vessels, which are con- 

 tained in the mesovarium. The significance of this process, 

 known from its principal feature as the decensus ovarioruin, 

 is unknown, but it seems to correspond in part to a somewhat 

 similar but more extensive descensus of the testis, found in 

 the male. 



To comprehend the relationships of the male organs in 

 mammals, it is best to begin again at the indifferent stage 

 [Plate III, a], which is thus seen to furnish the starting-point 

 for the explanation of the reproductive organs in both sexes. 

 While the accessory organs in the female are mainly the pro- 

 duct of differentiation in the Miillerian duct, the Wolffian duct 

 becoming vestigial, in the male it is the Wolffian duct that is 

 emphasized, together with the upper portion of the meso- 

 nephros, while the Miillerian duct is reduced to a few rudi- 

 ments. [Plate III, b.~\ As in male selachians and amphibians, 

 the anterior tubules of the mesonephros serve as vasa efferentia 

 for the conduction of the spermatozoa, but here they are used 

 exclusively for this purpose, while the nephrostomes, Bow- 

 man's capsules, and all parts of those tubules once associated 

 with the urinary function, are no longer developed. The 

 tubules are much convoluted and form a compact mass, closely 

 associated with the testis, the epididymis. The remaining 

 mesonephrotic tubules, those of the posterior, or exclusively 

 urinary portion in lower forms, never develop into functional 

 organs, but one or two of them, with blind free ends, may 

 retain their connection with the Wolffian duct, and form the 

 so-called vasa aberrantia, while the remainder, without con- 

 nection at either end, form a rudiment termed the paradidymis 

 ("Organ of Giraldes"), the homologue of the paroophoron, 

 of the female. The Wolffian duct, freed from all association 

 from urinary functions, becomes the exclusive spermatic duct, 

 the ductus deferens (vas deferens). The Miillerian duct is 

 lost along the greater portion of its extent, but leaves rudi- 

 ments at either end. The anterior end is represented by the' 

 appendix testis [hydatid of Morgagni], a knobbed body at- 



