170 THE AMERICAN NATURALIST. [VoL. XXXIV. 
Protula, and Nais, in which all divided individuals are sexual 
and alike in all respects, and which, they assert, cannot be 
regarded as a true alternation of generation. They summarize 
the budding of Autolytus as **a process that is to be placed 
alongside that of strobilization in the Scyphomedusz.”’ The 
presence of reproductive products in the parent stock of Auto- 
lytus throws doubt upon this comparison, and it appears to me 
more plausible to place these forms alongside the processes 
described by Brooks for the Hydromedusz (Mem. Bost. Soc. 
Nat. Hist., Vol. III, No. 12). Particularly striking in this respect 
is the similarity in the life history of Autolytus cornutus to the 
life history of Cunina octonaria, which he gives in a diagram as 
follows : 
Hydra — Medusa x « Eggs 
Egg — Planula — Actinula — Medusa x « Eggs 
Hydra = Medusa X < Eggs 
Here, according to Brooks, there is asexual multiplication with- 
out alternation of generation. . Since in Autolytus cornutus and 
Procerzea the parent stock also becomes sexual, just as does 
the actinula, we would have, in the life history of these syllids, 
nothing more than the parent stock undergoing asexual multi- 
plication, and forming stolons just as in the asexual multipli- 
cation of the actinula to form hydra. Taking the meaning of 
alternation of generation, as defined by Brooks in his work on 
the Hydromedusz, as the commonly accepted one, — a defini- 
tion which is also in accord with the descriptions given by 
Korschelt and Heider, — we would have in the syllids, for which 
a true alternation of generation has been claimed, no alternate 
generation at all, but simply a dimorphism resulting from an 
asexual multiplication of the parent stock. 
Without taking into consideration the morphological value of 
the stolon it would appear more plausible, therefore, to regard 
stolonization in Autolytus as a process akin to that of fission 
in other annelids — unlike the fission in Dero, AZlosoma, and 
other forms where the divided individuals are identical in all 
respects, in that it has direct reference to the distribution of 
the sexual products, yet similar to these in that all the resulting 
divisions are in reality sexual individuals. 
