278 Self-Mutilation in the [May, 
inducing self-amputation. The direCt application of elec- 
tricity to the ventral ganglia induced in one case the ampu- 
tation of a leg. 
These experiments prove that the self-amputation of the 
legs of the crab is a purely mechanical process, in which 
the will of the animal is nowise concerned. This is still 
more clearly proved by the following experiment : — A cap- 
tive crab, held fast by one leg, will exert himself to escape 
until quite exhausted, without ever coming upon the idea of 
escaping by throwing off the leg. If, however, the limb in 
question is pinched, or if the nerve of sensation is irritated 
in any other manner, the fraCture ensues at the usual point. 
Lastly, M. Fredericq has sought out the last remaining 
link among the organs concerned in this strange process, — 
the muscles whose aCtion mediates the fradture. He found 
that the integrity of the extensor muscle of the second joint 
is the essential condition for effecting the fradture. It is 
also necessary that the leg and the distal extremity of the 
second joint should find a resisting fulcrum, — either the 
finger of the experimentalist or the shell of the animal 
itself. 
It must still be noted that this reflex amputation is never 
attended with loss of blood, probably because the muscle 
which effedts the rupture remains contracted. 
M. Fredericq has observed such self-amputations in the 
lobster and in various crabs, in the hermit-crab, the 
shrimp, See. 
Subsequent observations made by M. Fredericq on a blind- 
worm have convinced him that the shedding of the tail is 
effedted here also by muscular contraction, and does not de- 
pend on any fragility of the part, as the name Anguis fragilis 
would seem to imply. To a dead specimen which weighed 
only 19 grms., a weight of 490 grms. had to be appended in 
order to tear off the tail. If a living blind-worm was sus- 
pended with its head downwards it twisted about in various 
directions, but without escaping by breaking off its tail ; but 
if the end of the tail was strongly irritated a series of lateral 
movements took place below the point of suspension, with 
the final result that the tail broke off, whilst the animal fell 
to the ground and fled. 
It was again caught and suspended by the stump of the 
tail. If the stump was rubbed with the fingers the animal 
broke off again immediately below the point of suspension, 
by the same mechanism of alternating contractions to the 
right and the left side of the body. Hence ^appears that, 
just as in the case of the crab, we have an aCtive fradture — 
