Dr. R. Greeff on Autolytus prolifer. 179 



connected with the parent, or immediately after their separation. 

 These segments newly formed by gemmation are then, just like 

 their predecessors, developed into a new generation of offspring, 

 and thrown off as apparent products of fission, whilst in reality 

 they only represent newly developed buds. This first gemmi- 

 parous prolitication is then again followed at the foremost point 

 of separation by a second gemmation, which, after attaining 

 matm'ity, probably gives place to a third, and so forth. In Syllis 

 prolifera, therefore, only the first generation thrown off con- 

 sists of true primitive segments of the primary animal, whilst 

 all the following ones undoubtedly originate for the most part 

 from newly developed segments (that is to say, by gemmation). 

 I say, for the most part, as according to Krohn's observations 

 [loc. cit. p. 72) it is certainly possible that, in a new budded 

 generation, some segments of the primary animal may 

 again participate in the division and be thrown off with the 

 budded portion, especially if these segments were previously 

 filled with ova &c., and had consequently attained a certain 

 degree of maturity. From these considerations, therefore, it 

 is clear that the processes of prolification in Syllis and Auto- 

 lytus^ although apparently so different, scarcely present any 

 essential differences when accm-ately examined. As we have 

 seen, both in Autolytus and Syllis, tlie first offspring are always 

 pure sprouts of fission, hut the following ones originate in 

 both hy gemmation. 



Another and different mode of asexual propagation occurs, 

 as is well known, in Nais, in which, according to the beautiful 

 and careful investigations of Max Schultze*, a segment of the 

 primary animal is thrown off for each new individual, and 

 employed in the formation of the latter. This segment is not 

 reproduced ; so that, during the continuance of prolification, 

 the parent animal loses as many segments as it throws off 

 young. Max Schultze justly names this process a reproduction 

 by fission, inasmuch as, for every new animal, an original 

 portion of the mother is absorbed. Nevertheless it should not 

 be overlooked that from this single primitive joint the actual 

 many-jointed animal is produced, only by the development or 

 budding forth from it of such a greater or less number of seg- 

 ments as may be necessary for the fully formed animal. In 

 this way, therefore, every new individual thrown off from the 

 primary animal is the product of a pure fission with sub- 

 sequent pure gemmation ; and thus we have here, again, to a 

 certain extent the. same point of view for the mode of propa- 

 gation as in Syllis and Autolytus, namely the combination of 



Wiegmanu s Archiv, 1840, p. 293, aud 1852, p. 3. 



