INTRODUCTION. 



9 



The vitalistic position appears to be the only logical 

 one.* Hence, any change which takes place, whether 

 normal or abnormal, is assuredly always of the nature 

 of a definite variation which, under normal con- 

 ditions — i. e. as a rule in Nature — takes the form 

 of a purposeful adaptation. In the case of so-called 

 " sports," or " monstrosities," which arise under ab- 

 normal conditions, as so frequently in cultivation, 

 the change is not of the nature of a purposive adapta- 

 tion in the usual sense of that expression ; it is often, 

 on the contrary, deleterious, as is shown by the in- 

 stance of completely double flowers. Here, under the 

 influence of a powerful abnormal stimulus, the plant 

 is constrained to take an unusual course in the develop- 

 ment of some of its structures, to readjust itself to 

 exceptional circumstances ; but even in these cases, as 

 in double flowers, a fasciated shoot, the complete 

 vegetative transformation of a flower into a shoot, the 

 virescent ovule, etc, there is in a sense a purposive 

 adaptation, for no doubt the plant adapts itself in the 

 best way it can to the abnormal conditions. In any 

 case the vitalistic position must here also be upheld, 

 for these abnormal structures are not of the nature of 

 haphazard, fortuitous variations,f are not the result of 

 the working of mere chemical and physical energies, 

 which are always blind, but are to be attributed, 

 equally with the normal structures found in Nature, 

 to the working of a regulative vital force. As Czapek 

 says : " My conviction is that nevertheless physiology 

 cannot be really identical with the chemistry and 

 physics of living organisms. If we consider the 

 explanation of the fundamental problems of life to be 

 the aim of physiology, physics and chemistry will pre- 

 sumably not be able to fulfil this great task for them- 

 selves alone. "J The able philosophy of Bergson also 

 thus concludes: "Before the complexity of an organism 



* For the philosophic proofs of it (three in number) see Driesch: 'The 

 History and Theory of Vitalism/ p. 208, 1914, and his other works, 

 t "Chance is the greatest enemy of thought" (Driesch, loc. cit.). 

 X 'Chemical Phenomena in Life,' p. 7, 1911. 



