author's abstract op this paper issued 

 by the bibliographic service, december 29 



THE RESULTS OF EARLIEST REMOVAL OF THE 



THYMUS GLANDS IN RANA PIPIENS 



TADPOLES 



BENNET M. ALLEN 



Department of Zoology, University of Kansas 



ONE FIGURE 



It is a matter of common knowledge that we are much in the 

 dark regarding the fmiction of the thymus gland. Results of 

 extirpation and of thymus feeding have been very conflicting. 

 Gudernatsch ('12, '14) claimed that administration of thymus 

 glands as food to Rana tadpoles retards metamorphosis and at 

 the same time stimulates grow^th. It has seemed to the writer 

 that Gudernatsch killed his tadpoles prematurely — that he should 

 have carried out his experiment at least a month longer than 

 he did. Romeis ('14) gained rather indifferent results upon this 

 question. Swdngle ('17), working in this laboratory, repeated 

 these experiments with uniformly negative results. He used 

 fresh thymus glands of young calves and found that his tadpoles 

 thus fed all underwent metamorphosis at the usual rate and in 

 typical fashion. Uhlenhuth ('18), in earher researches, found 

 that feeding mammalian thymus to larvae of salamanders caused 

 actual increase in growth in some while others show^ed slight re- 

 tardation. He concluded that this w^as due not to qualitative, 

 but to quantitative factors in the food. Later experiments 

 where the diet was exclusively made up of thymus-gland mate- 

 rial showed a decided resultant retardation in growth and differ- 

 entiation. He concluded that the thymus gland is deficient in 

 certain substances essential to growth. 



In a series of interesting experiments upon salamander larvae 

 he produces tetanus by means of thymus feeding. He concludes 



189 



