ARE FUNCTION AND FUNCTIONAL STIMULUS FAC- 

 TORS IN PRODUCING AND PRESERVING 

 MORPHOLOGICAL STRUCTURE? 



EDUARD UHLENHUTH, PH.D., 

 ROCKEFELLER INSTITUTE FOR MEDICAL RESEARCH, NEW YORK. 



Since the days of Lamarck the attempt has often been made 

 of explaining the genesis of the morphological structure of or- 

 ganisms through the theory of adaptation. A special form of 

 this theory is that of "functional adaptation" which was for- 

 mulated under this name byWilhelm Roux about 1880, and was 

 later elaborated by that investigator in an extremely extensive 

 and thorough manner. 



The most striking organic structures are those which like the 

 bones seem to be constructed on a definitely purposeful plan, 

 offering the largest amount of strength with the smallest amount 

 of material. Other organs, such as the muscles, increase in 

 size as a result of increased function. Roux named this phe- 

 nomenon "functional adaptation," while the structures under- 

 lying this principle he described as "functional structures." 

 He made a number of exceedingly careful anatomical studies 

 of such "functional structures." Endeavoring to explain the 

 genesis of such seemingly purposeful structures from a purely 

 mechanical standpoint, he found that they possessed exactly 

 that construction which was to be expected from a mathematical 

 calculation based on the principle of functional adaptation. 



In order to make clear the development of functional adapta- 

 tion, Roux fell back upon the most primitive particles of living 

 matter. In his opinion some of these particles have been adapted 

 to respond to functional stimuli, that is, they show a greater 

 tendency to proliferate in the presence of functional stimuli 

 than in their absence. Thus, those elements which were sub- 

 jected to stimuli soon predominated over those which were not 

 thus exposed. 



If functional structures consisted of such particles, they would 



