50 Messrs. S. G-. Shattock and C. GL Seligmann. [Dec, 14, 



It appeared possible that the epithelium of the testicular tubuli 

 would, under these circumstances, on proliferating, undergo degenera- 

 tion and atrophy from the pressure due to its own accumulation, 

 whereas the interstitial cells of the stroma might remain intact. This 

 result, however, did not ; ensue, but others, which we venture to record 

 as bearing on the problem under consideration. 



The forms selected were a breed of sheep (Herdwick), the male of 

 which is furnished with long recurved horns, of which the female is 

 quite destitute, and the common fowl. 



Observations upon Sheep. 



We owe to the kindness of two friends the opportunity of observing 

 many castrated sheep, as well as a certain number of others on which 

 some form of obliteration of the vas deferens had been practised. 

 Besides the horned (Herdwick) sheep already referred to, we made 

 observations upon the hornless Southdown, in which the results, 

 though less striking, are none the less constant. 



The results of occlusion of the vasa deferentia in the Herdwick 

 breed have to be compared with those following castration, and both 

 with the normal standard. Lambs of the same age were selected, 

 and the procedures mentioned were carried out at about the same 

 time. 



The occlusion of the vas deferens was effected a short way above the 

 testicle by the application of a silk ligature in two places and division 

 of the duct between. The animals were examined at different periods 

 during their growth, and were killed when fully developed at ages of 

 from 10 — 14 months. 



In those castrated either no horns appeared externally, and on 

 preparation the skull exhibited only two low osseous tubercles or horn- 

 cores, or very diminutive horns were produced, and beneath them a 

 slightly more prominent core than in the first case. 



In the ewe of the Herdwick breed there is no external trace of horn, 

 nor does the prepared skull show any osseous core. 



As contrasted with the results of castration, those of vasotomy are 

 very striking. The horns attain their full size, and the skull its 

 complete male characters, so that the head in no way differs from that 

 of the normal or intact ram. 



The form of the skull is modified by castration, not by double 

 vasotomy, the modification in question being obviously correlated with 

 the absence of horns. 



The skull of the castrated sheep, or wether, is less rugged, and the 

 bones thinner, but besides such general differences the plane of the 

 os frontis is continued backwards behind the orbits at a very obtuse 

 angle. 



In the intact ram, and equally after vasotomy, the plane of the 



