458 E. A. ANDREWS. 
formerly a connection of this nerve-stump with the main 
nerve-cord, an idea that is strengthened by the often immature, 
young appearance of the other terminal. We naturally suppose 
here that a wound has healed over in such a fashion that the 
old nerve-cord does not reunite, but that the distal end remains 
as an isolated stump while the proximal end grows down into 
the new terminal that is formed, abnormally, in place of the 
injured tissue, or at the place of injury to the tissue of the 
normal terminal. 
As there thus seemed some probability that operative inter- 
ference would result in the regeneration of the terminals in 
some cases, many experiments were performed on earthworms 
and upon Podarke. The results were negative. After the most 
various injuries,—removal of the posterior end, lateral, dorsal, 
ventral injuries, hemisection, cutting or cauterising,—there 
resulted a normal healing of the wound or else the regenera- 
tion of a normal terminal, never a duplication. This, however, 
is not astonishing, considering the rare occurrence of such 
duplication even in nature, where, no doubt, similar experiments 
are constantly being made. In fact, if the hypothesis be true 
that such bifurcations arise in process of regeneration, we 
would not expect it to occur often, as in nature both Allolo- 
bophora fetida and Podarke obscura very frequently 
lose and regenerate the posterior end, but very rarely produce 
a bifid termination. Thus, though such negative experiments 
tend rather to impress one with the remarkable tenacity with 
which the organism adheres to its normal form, and suggest to 
one’s mind the presence of some controlling law like that 
denominating the formation and regeneration of a crystal, they 
furnish no evidence against our assumption. 
Granting provisionally that bifurcation in Annelids in all 
cases may be, and in some cases must be, due to abnormal pro- 
cesses of regeneration, we may advance the working hypothesis 
that these processes consist in the interference with the 
normal position or conditions of the cells concerned in rege- 
neration. That is, we need not invoke the activity of any 
unusual amount or character of idioplasm, no special manipu- 
