100 BENNET M. ALLEN 



til at this is due to the presence in the thymus gland of a tetanj- 

 producing substance. He fails to produce tetany by feeding 

 thymus glands to frog tadpoles, and concludes that here the in- 

 jurious influences of the thymus gland are counteracted by the 

 parathyroid glands that here develop much earlier than in the 

 salamanders. 



The feeding experiments of Paton and Cioodall ('14) u])on 

 young guinea-pigs and rats are also negative. These authors 

 give an extensive discussion of the literature of the subject. 

 There is a good discussion of this field in general in a recent paper 

 by E. R. Hoskins (TS). 



Many experiments have been made upon the extirpation of 

 the thymus gland. A recent paper by Pari ('05) shows that 

 this produces no result in the guinea-pig. One of the most 

 widely quoted papers is that of Abelous and Billard ('96). These 

 authors claim that extirpation of the thymus gland in the young 

 or nearly mature frogs produced effects classified as follows: 



1. Dynamic: Little resistance to fatigue — muscular feebleness. 



2. Trophic changes: Skin discoloration, ulcerations. 



3. Blood changes: Oedema, increase of serum. 



Camia COO) tended to substantiate these results; but Pari ('05) 

 showed that these symptoms occurred in only a certain portion 

 of his experiment. The majority of his fi-cgs showed no symp- 

 toms of any kind as a result of thymus extirpation. He suspected 

 that the symptoms described by Abelous and Billard were caused 

 l>y infection. Pari observed bacilli in the frogs that showed the 

 desciibed symptoms, and by injecting these organisms into an 

 unoperated frog he was able to produce the same symptoms that 

 Abelous and Billard inte preted as a result of the extirpation of 

 the thymus glands. 



Hammar ('05), in a very thorough piece of work, was wholly 

 unable to find any effects resulting from thymus extirpation 

 when proper precautions were taken to guard against infection. 

 It is seen that there is strong evidence against the results which 

 A])elous and Billard attril)uted to thymus extirpation. 



It might still be arguetl that the thymus glands may have 

 an imi:)ortant function in regulating growth (hu'ing larval life. 



