Significance of the Internal Secretory System 157 



An Illustration of Neglect of Fact By Elementalist Theory 



These reflections lead to a still deeper level of the inherent 

 faultiness of elementalistic absolutism in biology, the toler- 

 ance which it engenders for ignoring relevant facts ; or 

 stated otherwise, of arbitrarily selecting from a great com- 

 plex of facts just those which suit the argument, and dis- 

 regarding all the others. For example, recall Loeb's ref- 

 erence to precocious leg-production in frog tadpoles as 

 though the effect of thyroid feeding stood alone rather than 

 as one among a great concatenation of effects, some con- 

 structive and some destructive, this complex of phenomena 

 constituting the metamorphosis of the young into the adult. 

 Loeb's use of Gudernatsch's results amounts to a positive 

 obscuration for the reader of what these important experi- 

 ments really teach. Only by the culling of facts to suit the 

 argument and the use of certain words and phrases, as 

 "influence," "responsible for," and so on, with equivocal 

 meanings, can these results be made to support the conten- 

 tion that thyroid substance is specific organ-forming sub- 

 stance for frogs' legs. The patent fact is that certain 

 mesenchyme and other cells of the larva are organ-forming 

 for legs, and there is no straightforward way of talking 

 about the causes of the transformation of a given group of 

 more or less undifferentiated tadpole cells into the much 

 enlarged and highly differentiated group called a leg, with- 

 out recognizing the whole organism as causal of the par- 

 ticular transformation. Probably no set of discoveries con- 

 cerning the development of the individual has ever been 

 made which so objectifies the means employed by the whole 

 in producing and correlating its constituent parts as those 

 on internal secretions ; and not the least significant fact is 

 that these substances are themselves produced by the or- 

 ganism. 



Even were Loeb's contention valid that thyroid substance 



