EXPERIMENTAL MORPHOGENESIS 159 



formation of two rings of red lines, inside the stem, these 

 rings being the primordia of the new tentacles. I removed 

 the terminal ring by a second operation soon after it had 

 arisen, disturbing in this way the process of restitution 

 itself : and then the process of restitution itself became 

 regulated. The organism indeed changed its course of 

 morphogenesis, which was serving the purposes of a 

 restitution, in order to attain its purpose in spite of the 

 new disturbance which had occurred. For instance, it some- 

 times formed two rings out of the one that was left to it, 

 or it behaved in a different way. As this difference of 

 morphogenetic procedure is a problem by itself, to be 

 discussed farther on, we shall postpone a fuller description 

 of this case of a restitution of the second degree. 



At present I do not see any way of proving independently 

 the autonomy of life by a discussion of these phenomena ; 

 their analysis, I think, would again lead us to our problem 

 of localisation and to nothing else ; at least in such an 

 exact form of reasoning as we demand. 



ON THE " EQUIFINALITY ' OF ItESTITUTIONS l 



I have told you already that Tubularia in the pheno- 

 mena of the regulation of restitutions offers us a second 

 problem of a great general importance, the problem of 

 the Eqnifinality of Restitutions. There indeed may occur 

 restitutions, starting from one and the same initial state and 

 leading to one and the same end, but using very different 

 means, following very different ways in the different 

 individuals of one and the same species, taken from the 

 same locality, or even colony. 



1 Driesch, Arch. Entw. Mech. 14, 1902. 



