254 



Notes on the Wolffian Body of Higher Mammals 



segment in the region of the dorsal border. This whole middle part of 

 the tubule has a much greater diameter than either the collecting tubule 

 at the glomerulus end or that which empties into the Wolffian duct. 

 The relative size of these various segments is shown in Fig. 8. Special 

 names might be given to the different parts of the tubule, but until 

 their significance is more definitely known this could be of little value. 

 There is, however, a very distinct division into a secretory and a conduct- 

 ing part. In the two convoluted segments, anastomoses sometimes 

 occur. It can readily be seen in examining the course of this tubule 

 how fluid forced into it from the Wolffian duct could be seen on the 

 lateral surface running in opposite directions. In comparing Figs. 7 

 and 8 the development of the tubule can be roughly traced. In Fig. 7 

 the large secretory loop S can already be recognized. The greatest in- 

 crease in length thus takes place in the segment between this loop and 

 the Wolffian duct. 



The epithelium lining the large secretory loop and the larger parts of 

 the middle segment of the tubule is represented in Fig. 9, S. T. The 

 cells are large, cylindrical, and somewhat rounded. The protoplasm is 



granular in the basal half of the cell 

 and quite clear in the other half. The 

 nucleus is oval and situated near the 

 centre of the cell, usually at the edge 

 of the granular half. The epithelium 

 lining the collecting tubules. Fig. 9, C. 

 T., is made up of cubical cells rich in 

 granules throughout. The nuclei are 

 round and stain deeply in hasmatoxy- 

 lin. The lines of demarcation between 

 these cells are not plainly visible, while 

 in the secretory portions of the tubule 

 each cell can be seen distinctly. 



Evidences of degeneration can be ob- 

 served in injecting the Wolffian tubules 

 of pigs 100 mm. in length. At this 

 stage the tubules sometimes inject com- 

 pletely, while in other specimens the 

 fluid runs only a short distance. In the male there is usually left a 

 small uninjected region opposite the testis. The tubules injected an- 

 terior to this become the epididymis. At this stage also many of the 

 tubules contain desquamated epithelial cells cast off into the lumen. 

 In pig's embryos I'iO mm. in length, the injection fluid cannot in 



Fig. 9. Section thi'ou^h Wolffian 

 tubules sliowing secreting: tubule (S. 

 T.) and coUecting- tubules (C. T.). B. 

 C, blood capillary. 



