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HAND-BOOK OF PHYSIOLOGY. 



there are developed from a new mass of blastema, the vasa efferentia, 

 coni vasculosi, and globus major of the epididymis; and thus is brought 

 about a direct connection between the secreting part of the testicle and 

 its duct (Cleland, Banks). The Wolman ducts persist in the male, and 

 are developed to form the body and globus minor of the epididymis, the 

 vas deferens, and ejaculatory duct on each side, the vesicula3 seminales 

 forming diverticula from their lower part. In the female a small relic 

 of the Wolman. body persists as the "parovarium"; in the male a similar 

 relic is termed the "organ of Giraldes." The lower end of the Wolman 

 duct remains in the female as the "duct of Gaertner," which descends 

 toward, and is lost upon, the anterior wall of the vagina. 



/ i 



FIG. 461. Section of intermediate cell-mass on the fourth day. m, mesentery; L, somatopleure; 

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

 germinal epithelium in which the primitive ova C and o, are lying; E, modified mesoblast. which will 

 lorm the stroma of the ovary; WK, Wolffian body; y, Wolfflan duct; x 160. (Waldeyer.) 



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

 along the body of the embryo toward 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 Wolman body, by the 

 invagination of the blind knobbed end of these diverticula by a tuft of 

 vessels (Fig. 463). 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 con- 

 dition remaining throughout life in many of the lower animals, e.g., 



