ee 
joint. If further evidence is asked it will be found, I think, in those 
cases in which the limb being cut off outside of the breaking -joint 
regeneration takes place from the cut-end. It is hardly possible for 
a case of this sort to arise under ordinary circumstances, for when the 
leg is injured outside the breaking -joint it is thrown off at its base. 
Perhaps a lively imagination may find some way of reconciling these 
facts with the popular dogma. I willingly leave this task to others, 
and prefer for myself the obvious conclusions from the facts. 
A few other points may be briefly mentioned. The regeneration 
of the new limb takes place more quickly at the breaking-joint than 
it does from inside or outside of this region. Here it may seem 
there is an opportunity to point out an obvious relation between 
regeneration and liability to injury, since it is always at the breaking- 
joint that regeneration takes place in nature. The conclusion would 
not, I think, be justifiable. All that can be claimed is that the con- 
ditions are more favorabe for regeneration at this point than elsewhere, 
and it is easily seen how this is the case. At the breaking-joint a 
smooth surface is left after the limb is thrown off. The muscles are 
not left exposed and the exoskeleton is broken off evenly. In con- 
trast to this we see that when the limb is cut off inside or outside 
of the breaking-joint a ragged surface is left exposed, and it is surprising, 
considering the nature of the cut surface, that any regeneration is 
possible. Yet although the process of regeneration is slower it is none 
the less perfect. If the claim is made, as is often the case, that the 
breaking-joint has been specially prepared as an adaptation for quick 
regeneration of a new limb then another question is raised and would 
have to be discussed on its own merits. It is not within the scope 
of this paper to take into consideration the question of the origin of 
this mechanism. We are concerned only with the question as to whether 
regeneration can take place in parts of the body that are not ordinarily 
subjected to injury. 
In this same category belongs perhaps the question as to whether 
the different kind of regeneration that takes place when the distal 
segment is cut off is not also an adaptation to the external conditions 
that surround the animal. It might be pointed out that if new tissue 
appeared at the end of the leg it would be worn off, since these legs 
are still used by the crab in its locomotion, and to infer from this 
that hence the regeneration in this region takes place beneath the old 
surface. Since, however, the structure of the end of the leg is different 
from that at its base I should expect to find in this, rather than in 
a process of adaptation, a sufficient explanation of the results. 
