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HANDBOOK OF PHYSIOLOGY. 



brought about a direct conDection between the secreting part of the tes- 

 ticle and its duct (Cleland, Banks). The Wolffian ducts persist in the 

 male, and are developed to form the body and globus minor of the epi- 

 didymis, the vas deferens, and ejaculatory duct on each side, the vesic- 

 ulae seminales forming diverticula from their lower part. In the female 

 a small relic of the Wolffian body persists as the " parovarium ; " in the 

 male a similar relic is termed the "organ of Griraldes." The lower end 

 of the Wolffian duct remains in the female as the " duct of Gaertner " 

 which descends towards, and is lost upon, the anterior wall of the 

 vagina. 



From the lower end of the Wolffian duct a diverticulum grows back 



FIG. 496. Section of intermediate cell-mass on the fourth day. m, mesentery; L, somato- 

 pleure; a', germinal epithelium, from which z, the duct of Muller, becomes involuted; a, thickened 

 part or germinal epithelium in which the primitive ova O and o, are lying; JB7, modified mesoblast, 

 which will form the stroma of the ovary; WK, Wolfflan body; y, Wolffian duct, x 160. (Wal- 

 deyer.) 



along the body of the embryo towards its anterior extremity, and ulti- 

 mately forms the ureter. Secondary diverticula are given off from it 

 and grow into the surrounding blastema of blood-vessels and cells. 



Malpighian bodies are formed just as in the Wolffian body, by the in- 

 vagination of the blind knobbed end of these diverticula by a tuft of ves- 

 sels. This process is precisely similar to the invagination of the primary 

 optic vesicle by the rudimentary lens. Thus the kidney is developed, 

 consisting at first of a number of separate lobules; this condition re- 

 maining throughout life in many of the lower animals, e. g. f seals and 



