Influence of Environment on Ammals 227 



certain authors claim to have succeeded in tliis, but the writer 

 wishes to apologize to these authors for liis iuahility to mnvinco 

 himself of the validity of their claims at the present moment. 

 He thinks that only continued breeding of these ai)parent 

 mutants through several generations can afford convinciuK 

 evidence that we are here dealing with mutants rather than 

 with merely pathological variations.^ 



What was said in regard to the production of new species by 

 physico-chemical means may be repeated with still more 

 justification in regard to the second problem of transformation, 

 namely, the making of living from inanimate matter. The 

 purely morphological imitations of bacteria or cells which 

 physicists have now and then proclaimed as artificially produced 

 living beings, or the plays on words by which, e.g., the regenera- 

 tion of broken crystals and the regeneration of lost limbs by 

 a crustacean were declared identical will not apj^eal to the 

 biologist. We know that growth and development in animals 

 and plants are determmed by definite although complicated 

 series of catenary chemical reactions, which result in the synthesis 

 of a definite compound or group of compounds, namely, nuclei tus. 



The nucleins have the peculiarity of acting as ferments or 

 enzymes for their owti synthesis. Thus a given type of nucleus 

 will continue to synthesize other nuclein of its own kind. This 

 determines the continuity of a species; since eacli species has, 

 probably, its own specific nuclein or nuclear material. Hut it 

 also shows us that whoever claims to have succeeded in making 

 living matter from inanimate will have to prove that he has 

 succeeded in producing nuclear material wiiich acts as a ferment 

 for its own synthesis and thus reproduces itself. Nobody lia."^ 

 thus far succeeded in this, although nothing warrants us in taking 

 it for granted that this task is beyond the i)ower of science. 



1 Since this was written the beautiful experiment.s of KaimneriT a.s wi«Il as 

 those of Tower seem to have furnished proof that external conditions can cause 

 hereditary changes in animals. 



