EXPERIMENTAL MORPHOGENESIS 



109 



ing organism is one whole in organisation and in function, 

 some sort of harmony of constellation, as it may properly be 

 styled, must be said to be one of the most fundamental 

 characters of all production of individual form. In establish- 

 ing this harmony we do nothing more than describe exactly 

 what happens : the harmony is shown by the fact that 

 there is a whole organism at the end, in spite of the relative 

 independence of the single events leading to it. 



But still another sort of harmony is revealed in morpho- 



Fio. 10. PLUTEUS-LARVA OF SPHAERECHINUS. 



The Intestine (i) is developed outside instead of inside (by means of raising the tempera- 

 ture) ; but the mouth (r) is formed in its normal place. S = Skeleton. 



genesis, by an analysis of the general conditions of the 

 formative actions themselves. In order that these actions 

 may go on properly the possibility must be guaranteed that 

 the formative causes may always find something upon which 

 to act, and that those parts which contain the potencies for 

 the next ontogenetic stage may properly receive the stimuli 

 awaking these potencies : otherwise there would be no 

 typical production of form at all. This, the second species 

 of harmonious relations to be described in ontogeny, may 

 be called causal harmony ; the term simply expresses the 



