FITNESS 29 



teins, 1 the chief of such things, and most 

 of the other biologically important sub- 

 stances have been obtained, and we are at 

 length in possession of exceedingly clear and 

 reliable ideas as to the chemical constitu- 

 tion of living matter. In fact, the nature 

 and laws of the chemical composition of pro- 

 toplasm are actually more certain than the 

 nature and laws of its physical structure. 2 



In this manner, by slow degrees, the de- 

 scription of living things has progressed, and 

 gradually the characteristics of life have 

 become less obscure and their aspects more 

 simple. It cannot be denied that many 

 traits like consciousness and inheritance are, 

 at least for the present, beyond the scope of 

 description in terms of matter and energy, 

 and the fundamental riddle shares this de- 

 tachment. 3 But the physico-chemical basis 



1 E. Fischer, " Untersuchungen iiber Aminosauren, Poly- 

 peptide und Proteine." Berlin, 1906. 



2 Substantial progress in the latter field is nearly all of 

 very recent date, almost wholly since the sudden rise of 

 physical chemistry. 



3 "But now, having confessed that Life as a principle of 

 activity is unknown and unknowable — that while its phe- 

 nomena are accessible to thought the implied noumenon is 

 inaccessible — that only the manifestations come within the 

 range of our intelligence while that which is manifested lies 

 beyond it; we may resume the conclusions reached in the 

 preceding chapters. Our surface knowledge continues to be 



