50 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



THE LIMITS OF PUKE DESCRIPTION IN SCIENCE 



We have analysed our descriptions as far as we could, 

 and now we must confess that what we have found cannot 

 be the last thing knowable about individual morphogenesis. 

 There must be something deeper to be discovered : we only 

 have been on the surface of the phenomena, we now want 

 to get to the very bottom of them. Why then occurs all 

 that folding, and bending, and histogenesis, and all the other 

 processes we have described ? There must be something 

 that drives them out, so to say. 



There is a very famous dictum in the Treatise on 

 Mechanics by the late Gustav Kirchhoff, that it is the task 

 of mechanics to describe completely and in the most simple 

 manner all the motions that occur in nature. These words, 

 which may appear problematic even in mechanics, have 

 had a really pernicious influence on biology. People were 

 extremely pleased with them. " ' Describing ' that is just 

 what we always have done," they said ; " now we see that we 

 have done just what was right ; a famous physicist has told 

 us so." They did not see that Kirchhoff had added the 

 words " completely and in the most simple manner " ; and 

 moreover, they did not consider that Kirchhoff never regarded 

 it as the ultimate aim of physics to describe thunderstorms 

 or volcanic eruptions or denudations ; yet it only is with 

 such " descriptions " that biological descriptions of given 

 bodies and processes are to be compared ! 



Physicists always have used both experiment and hypo- 

 thetical construction Kirchhoff himself did so in the most 

 gifted manner. With these aids they have gone through the 

 whole of the phenomena, and what they found to be ultimate 



