36 PROTOPLASMIC ACTION AND NERVOUS ACTION 



The general conclusion seems therefore justified that 

 the specific biological characters of an animal or plant 

 depend ultimately upon the specific chemical characters 

 of its proteins. The developing germ, or the growing 

 and metabolizing organism, builds up proteins of specific 

 constitution, and these, since they determine the specific 

 structural characters — with the correlative physiological 

 activities — of the organism, form the basis of its biological 

 specificity or special singularity as an organic species. 

 A fundamental problem, therefore, relates to the condi- 

 tion determining the synthesis of proteins of its own 

 specific type by each form of protoplasm. This problem 

 is as yet unsolved. Apparently the presence of proteins 

 of a certain composition and configuration promotes or 

 "catalyzes" the formation of proteins of similar or com- 

 plementary configuration. A general condition compar- 

 able with autocatalysis^ thus determines the specific char- 

 acter of the protoplasmic syntheses, but such a statement 

 merely defines the problem without solving it. The 

 problem, however, cannot be solved before it is clearly 

 defined, and its solution would unquestionably represent 

 a great advance in biological knowledge, since it would 

 involve the solution of the fundamental problems of 

 growth and heredity. 



There is some evidence of an identity, or at least 

 close chemical resemblance, between the specific proteins 

 of adult tissues or organs and corresponding or repre- 



^ For the comparison of organic growth with autocatalysis cf. J 

 Loeb, Biochem. Zeitschrift, II (1906), 41; T. B. Robertson, Arch. Ent- 

 wicklimgsmech., XXIV (1908), 581; Wfg. Ostwald, Roux's Vortrdge imd 

 Aufsdtze, V (1908). Chodat made a similar comparison for plant growth 

 in 1905 (cf. D'Arcy Thompson's Growth and Form, Cambridge Uni- 

 versity Press [1917], p. 132). 



