No. 399.] HISTORY OF AUTOLYTUS CORNUTUS I71 
Another aspect of this question is, however, presented by 
the morphological characters of the stolon itself. In the proc- 
ess of its development the stolon has been provided with a 
head very similar in structure to that of the parent stock, and 
with eyes even larger and more advantageously placed than 
those of the parent stock. The alimentary canal, moreover, is 
in a state of degeneration; the crowding of the reproductive 
products, particularly in the female stolon, has greatly reduced 
its calibre, and to all appearances it has ceased to function. 
Organs for the prehension of food are absent, a mouth-opening 
being formed simply by a union of the broken intestinal wall 
with the hypodermis, and it is quite evident, by the changes 
that have taken place in the alimentary canal of the mature 
stolon, and also by the continuous absence of food particles 
within it, that the stolon in its free-swimming stages does not 
feed. The stolon would then in reality reduce itself to a series 
of segments, some of which, in the male, or a large number of 
which, in the female, are gorged with reproductive products 
and provided with organs fitted for the proper distribution of 
the reproductive products—a condition similar to, but, by 
virtue of a head formation, more advanced than that which has 
been described for the sexual fragmentation in the Palolo worm. 
While the stolon must, for want of a better expression, be 
regarded as a distinct individual, in connection with the problem 
of alternation of generation the morphological value of such a 
Structure might well be questioned. 
The existence of a true alternation of generation in annelids 
so long as it is supported alone by the phenomena presented by 
Autolytus seems to me far from being established, and it is 
doubtful if a more extended study of any of the syllidians 
would add more to this proof. The presence of reproductive 
Products in even a smaller percentage of parent stocks than 
were found in Autolytus cornutus or Procerzéa could still hardly 
be looked upon as of purely accidental occurrence. Instead of 
regarding the presence of such sexual products in the parent 
Stock of Autolytus as accidental, it seems to me more plausible 
to regard it as the continuance of a more primitive condition in 
which the animal zz ¢o¢o assumed, at the ripening of the sexual 
