134 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



No Explanation Offered ~by a Chemical Theory 

 of Morphogenesis 



Though never set forth in the form of a properly worked- 

 out theory, the view has sometimes been advocated by 

 biologists, that a chemical compound of a very high degree 

 of complication might be the very basis of both development 

 and inheritance, and that such a chemical compound by its 

 disintegration might direct morphogenesis. 



Let us first examine if such a view may hold for the 

 most general features of organic morphogenesis. It seems 

 to me that from the very beginning there exists one very 

 serious objection to every chemical theory of form-building, 

 in the mere fact of the possibility of the restoration of form 

 starting from atypical localities. The mere fact, indeed, 

 that there is such a thing as the regeneration of a leg of a 

 newt to say nothing about restitution of the harmonious 

 type simply contradicts, 1 it seems to me, the hypothesis, 

 that chemical disintegration of one compound may govern 

 the course of morphogenetic events : for whence comes 

 the re-existence of the hypothetical compound, newly to 

 be disintegrated, after disintegration has been completed 

 once already ? And we even know that regeneration may 

 go on several times running from the same locality ! 



1 See my article in Biolocj. Centralblatt, 27, 1907, p. 69. The question is 

 rendered still more complicated by the fact that in the case of the regenera- 

 tion, say, of a leg it is not the original "morphogenetic compound" which 

 is again required for disintegration, after it has become disintegrated once 

 already, but only a specific part of it : just that part of it which is necessary 

 for producing the leg ! On the other hand, it would be impossible to under- 

 stand, on the basis of physical chemistry, how the isolated branchial apparatus 

 of Clavellina could be transformed, by chemical processes exclusively, into 

 a system of which only a certain part consists of that substance of which 

 the starting-point had been composed in its completeness. 



