Wound Reparation—A ctinian Tentacles 219 
or a prospective light. ‘The present ineffectual attempt at sur- 
vival may be the remnant of a phylogenetically ancient capacity 
for complete regeneration. Or, it conceivably affords a basis 
upon which the power of regeneration may subsequently be grafted. 
The latter possibility is a much less likely one in view of the gen- 
eral tendency of evolution toward more complex structural con- 
ditions and the inverse correlation of structural complexity and 
capacity for regeneration. 
The foregoing views regarding the significance of the behav- 
ior of fragments of a tentacle may well be abandoned, how- 
ever, in favor of a much simpler interpretation. Whether or not 
the reparation of the fragment is in any sense, however remote, 
of utility to the fragment itself or to the species, I think that the 
behavior of the fragment becomes to a certain degree intelligible 
when we view the detached tentacle merely as a fragment of the 
actinian and with no reference to its own fate. We have seen 
that the reparation process involves two phases; first, the pro- 
visional muscular control of the cut end and secondly the definitive 
structural closing of the end. Considering the first of these two 
phases and keeping in mind the character of the actinian organi- 
zation, it seems to me not surprising—indeed, to be expected— 
that the fragment of tentacle should behave like the attached 
tentacle. The actinian shows a rather low degree of specializa- 
tion of parts of the body as compared with higher Metazoa. It 
is a two-layered sac having certain appendages, which are merely 
hollow diverticula of the sac. All sections of the body wall, 
wherever taken, show the same arrangement of layers and cavities. 
There are no localized central nervous organs. ‘The fundamental 
coelenterate features of the actinian organization are repeated 
throughout column and tentacle. A piece of tentacle, then, is 
indeed a fragment of the actinian—that is, of the organism—but 
it is not a fragment of the organization, by reason of the fact that 
it embodies the essential features of the entire organization. ‘The 
distal cut end of a detached tentacle, therefore, differs from the 
distal cut end of an attached tentacle merely as to the quantity 
of a certain kind of organization lying proximad of them. It 
seems to me likely that the action of the muscles at the distal 
