THYMUS 137 



gland) is circumstantial at best and very meager. 

 It is equally difficult to prove that the thymus does 

 not produce a secretion, but the burden of proof 

 is upon those who support the former theory." 



A very remarkable experiment by Gudernatsch 

 must be cited here, though it should be noted at the 

 outset that another investigator, Swingle, chal- 

 lenges Gudernatsch's statements. The latter found 

 that by feeding tadpoles with thymus extract, their 

 growth could be accelerated to a remarkable de- 

 gree, but that metamorphosis to the frog state was 

 delayed. We have already seen in the chapter on 

 the thyroid that thyroid extract behaves in an op- 

 posite manner, in that feeding tadpoles with such 

 an extract accelerates the transformation into the 

 frog, but retards growth. Are we to assume that 

 the thymus is connected, for a time at least, with 

 thyroid activity? 



The general concensus of opinion is that the ex- 

 tirpation of the thymus does not necessarily result 

 fatally, though it does give rise to a disordered de- 

 velopment of the skeleton, such as may be seen in 

 a rickety child. Sciplades, a Hungarian investi- 

 gator, is of the opinion that osteomalacia, a disease 

 characterized by a softening of the bones, is brought 

 about by the absence of a functioning thymus. This 

 is based on experiments with young dogs whose 

 thymus had been completely extirpated. "The 



