J). W. CirTl.KR AND \j. DoNOASTKIl 09 



which appear similar to those t'ouml in the .same situation in the other 

 Ciises mentioned. Owing, however, to the fi.xation not being quite 

 perfect some of them have shrunk and the well-developed nucleolus 

 which is so characteristic an element of these cells in other cases, is 

 often replaced by granules lying in the nucleoplasm. The few nuclei 

 which have a definite nucleolus have few gi-anules in them and show 

 that they are comparable to the Sertoli cells already described. 



Our next examples of this class of organ are those of retained 

 testes in man and the dog. For these we are indebted to 

 Mr \V. McAdam Eccles, F.R.C.S., who kindly lent us a number of 

 slides. 



A section of a retained testis in the dog of an unknown age, again 

 showed no trace of spermatogenesis. The interstitial tissue was some- 

 what excessive in amount, but much less than in the tortoiseshell cat. 

 The tubules were small with thickened walls and were filled with 

 vacuolated strands of protoplasm ; in these at the margin were a large 

 number of nuclei. 



Sections of the retained testis in man vary considerably in different 

 cases, but some show very nearly the same set of characters already 

 mentioned above with one or two differences of a minor nature. The 

 interstitial cells are similar, showing the same characteristic nuclei and 

 vacuolation (Fig. 5), but are less in quantity than in the tortoiseshell 

 cat, and sometimes mingled with a considerable amount of fibrous tissue. 

 In the tubules there is a well-developed lumen, the protoplasm is scant 

 and drawn out into strands radiating into the middle, the nuclei of 

 the cells being placed round the periphery. A frequent feature is 

 the thickening of the walls of the tubules; this is referred to by 

 G. Bellingham Smith (Ouy's Hospital Reports, LIII. 1896) as a character- 

 istic feature of the retained testis in man, but is not present in the cat 

 or other animals examined by us. 



According t(j a paj)er by Griffiths in the Journal of Anatomy and 

 Physioloyij, Vol. xxviii. 1894, p. 209, the man with retained testes has all 

 the sexual instincts; this is in agreement with what we find in the 

 tortoiseshell cat, and as already stated, is in accordance with the 

 hypothesis that the stimulus of the sexual instincts arises in the 

 interstitial tissue. 



Attention must now be drawn to the figure and description in the 

 paper by Bouin and Ancel (p. 499), of the testis of a guinea-pig 

 examined 78 days after the ligature of the vas deferens. They say: 

 " Les spermatozoides disparaissent toutd'alxiril, puis les spermatides, les 



