348 



THE AMERICAN NATURALIST 



[Vol. LI 



To arrive at a proper estimate of the importance of a 

 general theory such as the one discussed in the present 

 paper, necessitates considerahle reflection. The path of 

 scientific progress is lu'-cn by the pitfalls of conservative 

 onipiricism, on the one 1i;iihI. mimI lt\- iliose of radical spec- 

 ulation, on tlie other. To tiic r.-idicjils ilie enzyme theory 

 ])resents an aspect of a pi tori seH'-cvidence; to the con- 

 servatives it seems to l)e a vague generalization with no 

 particular or specific facts to support it, approximately 

 on the same plane as the statement that "life is motion," 

 wliich Driescli says is about as useful as the proposition 

 tliat "I\;nit was a vertebrate." Eegarding the general 

 ( ii/ytiic theory, tlic following opinion has been ex])ressed 

 to ine i)i'ivately by an eminent zoologist. 

 The idea . . . is a perfectly familiar one. The trouble comes when 



problem, wliifli is what science demands if a i)ure speculation is to 

 become a valuable svnrki.i- liypothesis. For instance, how an auto- 

 catalytic molecule .-um!.! prndu-c. t!,,- phenomena seen in the division of 



must first be answered. I think, before we can make much advance in 



