ENDOCRINE FUNCTION OF THE THYMUS GLAND 337 



the case of the hemolysia production; that is, the antibody pro- 

 duction in the rabbit body by the injection of rat thymus is very 

 shght, if not entirely lacking, and more than that, the normal 

 complement of rat itself is entirely incapable of activating the 

 antithymus amboceptor, which is produced in the rabbit's body. 

 The same relation may be also true with regard to the anti- 

 testis serum produced in the rabbit by the injection of rat testis 

 emulsion. I assume, therefore, that the negative results of 

 Moorhead's experiments may be explained in the same way; 

 that is, the antibody production in the animal is very faint and 

 the complement is utterly incapable of combining with the 

 respective amboceptor to produce a true cytolysis. 



I wish that Shimizu could show us that the hemolysin production 

 in the rabbit after the injection of dog corpuscles is very active 

 and that the hemolysin formed could combine with the normal 

 dog complement to produce a true hemolysis. By this method 

 of verification I think our doubt cast upon the validity of his 

 conclusion would be greatly diminished. Following Hoskins in 

 his discussion of Hewer's work, we may say here, "Since com- 

 plete removal of the thymus has no such effects as described by 

 Shimizu in the dogs after the injection of his thymolysin-serum, 

 and unhealthy animals do not grow very well, Shimizu must prove 

 that his treatment did more than injure the health of his animals." 



Since we are unable to get a positive result in our experiment, 

 and have a reasonable explanation for the negative result, we 

 cannot believe that the thymolysin can do more in vivo than 

 the total removal of the thymus could do. We are therefore 

 inclined to the view that the retardation of the growth of the 

 injected dogs in Shimizu's experiments, in comparison with the 

 control, may have been caused to some extent at least by the 

 'primary anaphylaxis' due to the serum injection. 



If Shimizu's thymolysin were not so strictly specific in reac- 

 tion in vitro (in his paper he did not give any data for tests in 

 vitro) , as is the case in my antithymus serum, then his thymoly- 

 sin-serum, when injected, might be expected to cause some effects 

 other than those in the thymus gland, supposing that the comple- 

 ment can be combined with the amboceptors sufficiently to pro- 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, NO. 2 



