170 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



dark ; light is necessary for their morphogenesis. Is, there- 

 fore, their growth in the presence of light to be called a 

 morphological " adaptation " to light ? Certainly not : they 

 simply cannot originate without light, because they require 

 it for some reason. It is precisely here that our conception 

 of light as a " means " of morphogenesis is most fully justi- 

 fied. There are many 1 such cases ; and there are still 

 others of an apparently different type, but proving the 

 same. All pathological forms produced in plants by animal 

 parasites or by parasitic fungi could hardly be called adapta- 

 tions, but must be attributed to some abnormality of means 

 or of stimuli. It may be that the organism reacts as well 

 as possible in these cases, and that if it reacted otherwise 

 it would die we know absolutely nothing about this ques- 

 tion. But even then there would only be some sort of 

 regulation in the process of pathological morphogenesis, but 

 the process itself could hardly be called adaptive. 



So far we have only learned what is not to be regarded as 

 morphological adaptation. No response to external forma- 

 tive stimuli is in itself an example of adaptation, nor are 

 processes dependent for their existence on any kind of 

 condition or means to be called, simply because they are 

 dependent on them, adaptations to those agents. What then, 

 after all, is a morphological adaptation ? 



Let us remember what the word adaptation is really to 

 mean in our discussions : a state of functioning is adapted 



1 Klebs has suppressed the reproductive phase of organisation altogether, 

 in fungi as well as in flowering plants, or has made it occur abnormally early, 

 merely by changing the "external conditions " and by altering the " internal " 

 ones correspondingly. There is hardly anything like an adaptation in these 

 cases, which, by the way, offer certain difficulties to analysis, as the boundaries 

 between "cause" and "means" are not very sharp here. 



