430 THE SEMINAL TUBULES. [sect. 197. 



cells, but recently, 0. Becker has made the interesting observation, 

 that the chief part of this epithelium is of the ciliated variety. 

 I have found the statements of this observer to be fully confirmed, 

 in all essential respects, by an examination of the testicles of a 

 suicide. Here, in the vasa efferentia, was seen a simple epithelium 

 with cylindrical or conical cells (o'Oi'" to 0-015'" long), brownish 

 nuclei in their interior, and cilia of 0*003'" to 0*004"' l° n g- In 

 the coni vasculosi the cells were similar, but somewhat longer, 

 and the ciliated edge was 0*005'" broad. At the entrance to the 

 canal of the epididymis, extending as far as its middle, there 

 appeared a single layer {Becker says several layers) of epithelium, 

 whose cells were cylindrical, of enormous length (0-02'" to 0*025'"), 

 with delicate dark nuclei placed below the middle of the cell ; the 

 cilia were often grouped in tufts, and were as long as o*oi'" to 

 col 5"'. In the middle of the epididymis, I remarked a few 

 scattered cells of this sort, but I could not convince myself that 

 these had not come off from a part higher up, especially as shorter 

 cells without cilia were also found here. Cells, similar to those 

 last mentioned, were contained also. in the tail of the epididymis, 

 and in the beginning of the vas deferens, only that many of those 

 in the last situation showed a clear margin of greater width. I 

 saw no ciliary action in this case ; but I have satisfied myself of its 

 existence in the lower mammalia, and I can confirm the observation 

 of Becker, who saw it in the human testis after extirpation, that 

 the direction of this action is towards the vas deferens. 



The contents of the seminal tubules are not the same at all pe- 

 riods of life. In boys and young animals, there are found in the 

 narrow tubules nothing but small clear cells, the outermost of which 

 may be regarded as epithelial, though they are not always clearly 

 distinguished from the others. At the period of sexual maturity, 

 the elements contained in the seminal tubules increase in size simul- 

 taneously with the enlargement of the latter, and when the formation 

 of the semen is actually established, they appear as clear, round cells, 

 0*005'" ^0 0*03'", and as cysts which inclose a variable number (1 

 to 10 or even 20, according to their size, fig. 181, a) of clear 

 nuclei, 0*0025'" to 0*0035'" m diameter, with nucleoli. In many 

 cases, an epithelium is not distinguishable at this period, the 

 seminal tubules being wholty occupied by the above-mentioned 

 cells ; at other times, and more especially in those advanced in 

 years, it is present, and then consists of fatty or pigmentary cells, 

 which surround the other elements. These cells now, in whatever 

 manner they appear, are the precursors of the semen, which, in 

 the mature condition, is made up of an extremely small quantity 



