AND ITS INHABITANTS 99 



With this in mind we may briefly survey some of the modern 

 scientific conjectures which attempt to formulate the phe- 

 nomena attendant upon the evolutionary origin of matter in 

 the living state from the inorganic upon the earth. 



Pftiiger's theory. Assuming that the surface of the earth 

 was once incandescent, Pfluger has offered a suggestive theory 

 the crucial points of which turn on the chemical characteristics 

 of the proteins. He emphasizes that there is a fundamental 

 difference in the nitrogenous radicals of what he terms "dead" 

 proteins, as egg albumin, and "living" proteins taking an active 

 part in the economy of protoplasm, since the nitrogenous 

 decomposition products of the latter either contain the cyano- 

 gen radical or can be artificially produced from compounds of 

 cyanogen by atomic rearrangement. This suggests to Pfluger 

 the probability that the cyanogen radical is an integral part 

 of the molecular complex of living proteins and since in the 

 formation of cyanogen a large amount of heat is absorbed, it 

 follows that this radical possesses a large amount of internal 

 energy and thus with it there is "introduced into the living 

 matter energetic internal motion." 



Pfliiger's idea that the protein molecules of living proto- 

 plasm owe their diagnostic characteristics, in particular their 

 lability, to cyanogen is supported, He believes, by certain 

 analogies, which we need not consider, between cyanogen com- 

 pounds and "living" proteins. Indeed, he says, the "similar- 

 ity is so great that I might term cyanic acid a half living mole- 

 cule." "When we think of the beginning of organic life, we 

 must not think primarily of carbonic acid and ammonia; for 

 they are the end of life, not the beginning." 'The beginning 

 lies rather in cyanogen." Pointing out that cyanogen and its 

 compounds arise only in an incandescent heat, he holds that 

 "life is derived from fire, and its fundamental conditions were 

 laid down at a time when the earth was still an incandescent 

 ball." Thus living material owes its genesis to cyanogen com- 



