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,[62] 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! [62] See my article in *Biolog. Centralblatt*, 27, 1907, p. 69. The question is rendered still more complicated by the fact that in the case of the regeneration, 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 understand, 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*. But, if we intentionally disregard this difficulty, in spite of its fundamental character, how could the hypothesis of chemical disintegration give the reason for the differentiation of our harmonious-equipotential systems, with special regard to the localisation of it; how could it account, in other words, for the appearance of typically localised specifications in an organ for which no external localising causes can be predicated?