Fission and Oemmatioji ui the Animal Kingdom. 27 



" terminal gemmation " as " growth in the longitudinal axis 

 with subsequent transverse fission " *, &c. 



To proceed to generalizations before we have acquired 

 complete clearness as to fundamental notions is always a 

 critical undertaking. I therefore hold it to be absolutely 

 indispensable, though other investigators may perhaps at 

 once consider it superfluous, to find out what we are to term 

 fission and what is to be designated as gemmation. 



Since I was thus of necessity led, from the interpretation 

 of the reproduction of Microstoma in particular, to a general 

 investigation of the doctrine of fission and gemmation in the 

 whole Animal Kingdom, a simple consideration indicated tlie 

 path which 1 had to adopt for the latter. It was self-evident 

 that it was not a question of somehow or other distinguishing 

 fission and gemmation from one another, but of demonstrating 

 the natural characteristics of the two forms of reproduction, 

 or at least of one of them. " Natural " characteristics are, 

 however, those which, in the notional meaning of the term, 

 which is also otherwise united therewith, admit of being 

 enumerated without compulsion. 



The word " gemmation " denotes exclusively biological 

 processes, to which there is nothing corresponding outside 

 organic nature. Nevertheless, owing to the multifarious and 

 consequently ambiguous application of this expression, it is 

 absolutely impossible to state what gemmation signifies 

 within the limits of the Animal Kingdom. In one case 

 tentacles " bud " upon a polyp, in another proglottids from a 

 scolex, in a third segments at the growing .hinder end of an 

 Annelid, or, again, whole individuals or parts thereof " bud " 

 from and upon a parent, and in the ontogeny of Vertebrates 

 we even meet with a '' caudal bud." The only feature in 

 common which all these different processes can well have is 

 that somethinQj somewhere and somehoio, grows upon an 

 animal. 



I therefore reverted to " fission," a word with which every- 

 one connects a distinct idea, which is first acquired outside 

 the vital processes. This gives us an objective foundation 

 for further developments. 



The following statements therefore proceed from the 

 starting-point of fission. I have put them as shortly as 

 possible, because I did not wish to prolong the present paper 

 to an unseemly length. 



Whether the attempt which I have made to establish a 



* C. Claus, ' Untersucliungcn iiber die Organisatiou uud Entwicklung 

 der Medusen,' Leipzig, 188.'3, p. 17. 



