8 
The small fourth and fifth pairs of thoracie legs are used by the 
crab in bracing itself against the shell and in pushing its body out 
of the shell. They are not used in walking. As I pointed out in 
a preceding paper these legs do not seem to be often (if ever) in- 
jured, and yet they regenerate readily. During the past summer I 
have examined further the power of regeneration of these legs. The 
results have shown that they also may regenerate at any level, 
and behave in much the same way as do the more anterior legs that 
possess the breaking-joint. 
WFISMANN has raised a curious point in criticising my previous 
paper. I had shown that the terminal pair of abdominal appendages 
in the hermit-crab, that are peculiarly modified for anchoring the 
animal in its shell, can regenerate very quickly. These hard append- 
ages on the end of a very soft abdomen can scarcely ever be in- 
jured without serious injury to the abdomen itself; and if the latter 
is injured the crab speedily dies. WEISMAnN attempts to explain the 
regeneration of these appendages by saying that at some time in the 
past, before the crab took up its abode in a shell, it might have ac- 
quired the power of regeneration in these parts of the body (for they 
were then exposed to danger), and that this power had never been 
lost even after the appendages had changed their form and function. 
WEISMANN further points out that if his hypothesis be true then we 
should expect to see regenerate not the appendages characteristic of 
the hermit-crab of the present day, but appendages like those of an 
remote ancestor whose germ-plasm for regeneration has been handed 
down to the present time. It may be, therefore, not without interest 
to those who still cling to Weısmann’s theory of praeformation as an 
explanation of regeneration to examine 
the series of figures drawn in Figs. 16—19. 
These figures show the regenerated 
y last abdominal appendages of the hermit- 
crab. In Fig. 16 the larger left appendage” 
Fig. 16, Fig. 17. Fig. 18. Fig.19. has regenerated after being cut off at its 
basal segment. It is like the typical ap- 
pendage of the hermit-crab except in point of size. In Fig. 17 the new 
appendage is the small right one, and it too is like the typical append- 
age. In Figs. 18 and 19 the right and left appendages of the same 
individual are shown. Only one appendage had been cut off, but it has 
so completely regenerated that it is impossible to tell which is the 
new one. 
There can be no question of the similarity of these appendages 
