166 CARL R. MOORE 



upon the penis, testis, sperm sacs, or psychical nature of the 

 animal ; for it has been functioning as a male animal, having been 

 used for breeding, and histological sections show that the seminif- 

 erous tubules are actively producing spermatozoa. 



In the light of many researches, it is wrong to assume that 

 these grafts, on account of their being smaller than the normal 

 gland, are not able to exercise their full function. The work of 

 Pezard, Stotsenburg, Sand, Steinach, and others leads one to 

 assume that even a small functional part of one sex gland is able 

 to maintain the typical somatic and psychical characters of the 

 animal represented by the small graft. 



Many of the grafts described in section V have evidently 

 suffered considerable degenerative changes and many of the 

 transplants have been entirely resorbed. This, however, is 

 true in many autoplastic grafts, and hence cannot be accounted 

 for by assuming that one sex gland secretes a substance that 

 inhibits the growth of the opposite one. If a testicle and ovarian 

 grafts exist in the same animal in a functional condition for a 

 period of approximately one-fourth or one-fifth the entire natural 

 sexual life of the animal, one cannot assume that a secretion 

 from each gland causes a destruction of the other. 



Sand states that he was entirely unable to obtain growth of 

 a subcutaneous transplant in an animal of the opposite sex if 

 the sex glands of the latter were present. He develops quite an 

 elaborate hypothesis to explain the negative results, but again, 

 my own observations indicate that no such hypothesis is neces- 

 sary, for positive results have been obtained in many cases. 



In the entire series of grafts, with one possible exception, there 

 are no indications that ovulation has occurred, and it is inter- 

 esting to consider the possible factors involved. Leo Loeb 

 determined that by underfeeding female guinea-pigs sterility 

 could be produced. Under the conditions of the experiment, 

 the follicles behave in a manner somewhat similar to the follicles 

 in the grafts of the rat ovary; instead of proceeding in their 

 normal development, they become atretic. It may be possible 

 that in the new environment in which the transplanted ovary 

 is placed, vascular connections are not entirely sufficient to make 



