Further Examination of the Cell-Theory 225 



appear in regular succession till the adult stage with its 

 distinctive characters were reached. The great point to he 

 emphasized is that if we are guided strictly by the observa- 

 tional and rational methods by which all our knowledge of 

 organic development has been built up, we see that the ef- 

 fort to conceive germ-cell promorphology or pr()])hysiology 

 in terms of representative units succeeds only in so far as 

 we deceive ourselves into believing that we know what we 

 do not know, and probably never can know, about the struc- 

 ture and functions of the germ, and by thus deceiving our- 

 selves, believe ourselves relieved of the necessity of endeavor- 

 ing to learn what the actual structure and function of the 

 germ is. 



The metaphysical ])romorphology and prophysiology of 

 the germ which, culminating in the "determinants" of Weis- 

 mann, have befuddled the thinking of many biologists, hold 

 exactly the same place in the logic of biology that phlogis- 

 ton held for well nigh a century in the logic of chemistry. 

 There is surely something in the wood that is a cause of 

 the flame, so why not say the characters of the flame are 

 "carried" in the wood by units capable of doing that sort 

 of thing? And how easy and complete the explanation of 

 flame would be on that basis ! For minds of such cast as 

 that of Joseph Priestley (about the last ardent defender of 

 phlogiston) and as those of Weismann and his disciples, 

 explanations of this sort appear to have great fascination. 



It is probably implied, if not definitely contended, by 

 some present-day geneticists, that the methods of analysis 

 employed by them, those, namely, of experimental breeding, 

 the application of Mendelian principles of inheritance, and 

 the correlation of these with chromosomal studies, are a 

 refutation of the conceptions above set forth. As a matter 

 of fact, though, the results of genetical analysis, so far as 

 they are objective and not purely speculative, are entirely 

 confirmatory of the conceptions. 



