Chapter 2 



Transplantation and Individuality in Higher 

 Invertebrates and in Amphibia 



In this chapter we shall analyze individuality first in lumbricidae, which 

 represent a transitional form between the very primitive invertebrates, 

 already discussed, and the more differentiated echinoderms and arthro- 

 pods. These latter will then be considered, and lastly, amphibia, as representing 

 a less highly developed type of vertebrate. 



A. Transplantation and Individuality in Annelids 



The lumbricidae differ from the planarians in a considerably greater fixity 

 of their organs and presumably in a correspondingly greater specificity and 

 fixity of the substances on which the differences between organs depend 

 (organ differentials). While the organs have not yet become entirely rigid, 

 still the differentiation between head and tail parts is more fixed than in 

 planarians. In accordance with this change in the organs we find a greater 

 differentiation in the organismal differentials, as is indicated in the trans- 

 plantation experiments on lumbricidae which have been carried out especially 

 by Korschelt and his associates, Joest, Rutloff, Leypoldt, Harms, Rabes, and 

 more recently by Mutscheller. The earlier of these experiments antedated the 

 majority of the investigations on coelenterates and planarians. At that time 

 attention was focused on problems which have since receded into the back- 

 ground. Thus the problem as to the significance of a reversion of polarity in 

 transplantation, which had been introduced largely through the investigations 

 of Voechting in plants, dominated research to a large extent at this earlier 

 period, and even much later we find Schoene studying polarity in transplan- 

 tation of vertebrate skin. 



As to polarity, two questions might be asked: (1) Is there inherent in 

 these organisms an orientation of their constituent parts comparable to the 

 organization of a magnet, and is it therefore necessary that the transplant be 

 inserted into the host in a definite direction if transplant and host are to be 

 mutually compatible? As far as is known, this does not hold good in the 

 animal series. (2) Do the actions of contact substances and of distant sub- 

 stances exert different influences on regenerative processes, and in particular 

 on wound healing, in a normal and a reversed orientation of the transplanted 

 piece? This may be the case in the more primitive organisms, where regenera- 

 tive processes of an integrative character play a much greater role than in 

 the higher organisms, and where the organ differentials are not yet so rigid 

 as to prevent heteromorphosis. However, in some instances certain subsidiary 

 factors may differ at the two poles of a transplant and then such factors may 

 play a role also in higher organisms. 



218 



