12 ADAPTATION AND DISEASE 



The Method of Attack 



There are two ways by which problems of this nature are 

 a priori most likely to be solved, namely, by experiments upon 

 the very simplest and, again, upon the most complex forms of 

 life. I see that Dr. Bayliss as a physiologist casts doubts upon 

 the value of the former as compared with the latter, 1 pointing 

 out that their very simplicity is in the majority of cases a dis- 

 advantage, and quoting Claude Bernard to the effect that the 

 lower (unicellular) forms of life possess all the essential pro- 

 perties which exist in the (multicellular) forms higher in the 

 scale, but possess them in a confused state, distributed, as it 

 were, throughout the organism. The one organic cell fulfils 

 a variety of purposes which in the higher organisms are relegated 

 to distinct groups of cells. While freely admitting this conten- 

 tion as regards the study of function, it has to be pointed out 

 that for problems of adaptation and heredity the unicellular 

 organisms possess the supreme advantages of rapid reproduction, 

 coupled in the very lowest forms (according to our present 

 knowledge, or want of knowledge a ) with a complete absence 

 of the disturbing influence of sex and conjugation. There is, 

 that is, a greater likelihood of obtaining results, and the experi- 

 ment becomes simpler, where we can in the course of a few hours 

 subject one hundred generations to a particular alteration of 

 environment, than when weeks, months, or years elapse before 

 one new generation shows itself. In the latter case, to obtain 

 results, either the alteration of environment must be made 

 intensive to a degree that is likely to interfere with various 

 vital functions, or, exhibited in a less intensive form, must act 

 over unduly long periods. I know that certain biologists are 

 unwilling to regard the products of asexual binary division of 

 the bacteria, or the torulae of yeast (the results of budding), 

 as true generations, and deny the right to regard the individual 

 bacillus as an individual. One very distinguished biologist 

 went so far as to declare to me that a long cultivation of a 

 bacterial growth is " one continuous individual," in other words, 



1 W. M. Bayliss, Principles of Physiology, 1915, p. 291. 



* For myself, with sex so widespread an attribute of living beings, I confess 

 that I am wholly prepared to find that the schizomycetes, or some of them, 

 exhibit a sexual, or conjugation, phase. 



