20 ON GERMINAL TRANSPLANTATION IN VERTEBRATES. 



no difference. The efferent parts of the tubules degenerated, though more 

 slowly than the sperm-forming parts. The author is inclined to attribute 

 non-success, in part at least, to the absence of trophic stimulation of the 

 nervous system, though he admits his view is far from being proved. 



Zalachas in 1907 gives the result of autoplastic transplantation in frogs, 

 in which he found living sperm preserved after one month. He does not 

 claim that this proves activity of the transplanted gland, for as a control 

 he found (completely degenerated but containing active spermatozoa) a 

 testicle which had been for one month in a sterile tube. Zalachas also 

 transplanted testicles of very young dogs into older dogs, and in seven 

 cases got almost complete degeneration at the end of one month. 



Foges (1898) extended the result of Lode's work on caponizing cocks, 

 without obtaining any very convincing results. 



Foa (1901), in a very able paper, sums up the results of others, and then 

 describes in detail his own work on dogs, autoplastic and homoplastic, which 

 gave negative grafts after one month. The organs of three-day old dogs 

 were used for the transfer. In another experiment a part of one of these 

 testicles was carefully sutured by the tissues to another testicle, in which, 

 though left in situ, a part of one end had been cut off. The cut faces of 

 the two testicles were thus brought face to face. Complete degeneration 

 took place both in the graft and in the remaining portion of the animal's 

 own testicle. 



Foa therefore combats the theory of the lack of efferent ducts suggested 

 by Ribbert. His results are the same whether the testicle is embryonic or 

 adult, whether whole organs or parts of organs are used. Foa gives weight 

 to traumatism, brought about by the operator, as the essential cause of 

 degeneration. 



We believe that the results of Maximow (1899), in the study of the regen- 

 erative capacity of the testicle after artificial wounds, show the testicular 

 tissue to be of a very delicate nature, easily unbalanced b> slight mechan- 

 ical disturbances. The work of Cevolotto (1909) goes far towards strength- 

 ening this view. This author made a careful study of the cell changes in 

 autoplastic transplantation of bits of testicular tissue into the tissue of the 

 ear. His results, in a word, show the harmful influence to the highly 

 differentiated epithelial tissue, which last is quickly converted into embry- 

 onic tissue. Sertoli cells increase and epithelial giant cells appear. 



With this idea in mind the results of Guthrie (1910) are indeed surpris- 

 ing, though it must be confessed that a review of the literature shows the 

 cock to be a very likely subject for transplantation experiments. Guthrie 

 reports normal testicular structure existing in grafts after four months. 

 He hopes to produce artificial fertilization in hens from such testicular 

 grafts in continuation of his experiments on the effect of the foster-soma 

 on engrafted germ -cells. 



