REGENERATIVE POTENCIES OF DISSOCIATED CELLS. 381 



our investigations lies in the rather anomalous fact that we have 

 not been successful in obtaining regeneration of the complete 

 organism from the dissociated cells. In our experiments the 

 restitution masses, by some rearrangement or metaplastic process 

 taking place among their conglomerated cells, formed tissue 

 aggregates histologically reduplicating the structure of the parent 

 organism, but in a quite irregular and apparently meaningless 

 manner.'' 



Two features in this quotation call for brief consideration, 

 that included in the first sentence, and that which I have itali- 

 cized in the last. It will have been noted in the accounts given 

 in the earlier sections of this paper that I have given a number of 

 cases comprising the exact equivalent of the failure they mention. 

 This point will be further noted in a later paragraph. To the 

 second feature it is only necessary to state that in normal hydroid 

 development the entire process is often "quite irregular and 

 apparently meaningless,'' frequently more so than they found in 

 the cases concerned. In a final paragraph the authors say: "Our 

 experiments have resulted in the production of masses that are 

 certainly abnormal and pathological, but nevertheless we would 

 submit that the segregation and rearrangement of the cells after 

 isolation, and the comparatively long duration of life of the 

 tumor-like masses to which they give rise are facts of considerable 

 theoretical interest." 



In this quotation I have italicized the points to which it seems 

 necessary to make some reference. It may be admitted that in 

 some sense such restitution masses are abnormal, in that the very 

 process by which their dissociation was brought about was 

 presumably abnormal. But that the resulting restitution masses, 

 involving as they have the regenerative potencies of the com- 

 ponent cells, is abnormal I must seriously challenge. Again, the 

 assumption that they are pathological I should emphatically 

 doubt. The writer once submitted a series of preparations of 

 embryological material to a well-known cytologist and received 

 the (at that time) very disconcerting comment, "your prepara- 

 tions appear to have been made from pathological material." 

 Yet from that very material I had been getting living embryos by 

 the hundred ! So in the present case to designate as pathological 



