vin DARWINISM AND HOLISM 19S 



between the accidental variations and Natural Selection, 

 and there is no clear reason why or how this clash should 

 not produce chaos and disaster, rather than the harmonies 

 and adjustments which actually characterise the relations 

 of animate and inanimate Nature. Darwin's theory, even 

 if it were wrong in its details, certainly served to explain 

 and render intelligible the broad facts of the order, ad- 

 justment and progress observable in animate Nature. His 

 successors' theories, even where they are correct in de- 

 tail, fail to explain these facts, and make of the world of 

 life as a whole an unintelligible and in some respects an in- 

 credible affair. 



It would, however, be a serious mistake to look upon the 

 more recent developments in the nascent science of Genetics 

 as covering the whole wide field of the Darwinian theory. 

 So far as I know, they have no such scope, nor are they so 

 intended or understood by those who are responsible for 

 the very important researches in Genetics now being success- 

 fully carried on in biological laboratories. These researches 

 are intended to follow up a special line which was first 

 opened up by the experiments of the Abbot Mendel of 

 Brunn in the time of Darwin. They occupy a very restricted 

 area of the whole field of organic Evolution, and are really 

 concerned only with the elucidation of the special set of 

 problems arising from the crossing or hybridising of races, 

 varieties or definitely distinct variations. Those problems 

 centre around the important question how biological char- 

 acters already in existence, whether patent or masked, be- 

 have when brought into contact with each other. Mendel 

 found that certain existing characters behaved as firm and 

 stable units, very much as atoms or molecules do in chemical 

 combination, and he also discovered the law of the propor- 

 tions in which these unit characters are reproduced in the 

 offspring. Thus if individuals of dominant character a are 

 crossed with individuals having recessive character b, then 

 in the second filial generation the numbers of individuals 

 respectively with a characters, and b characters, and mixed 

 a and b characters are given by the algebraic formula 



