138 Proceedings of Royal Society of Edinburgh. [jan. 30 , 
vermin, or from any irritative condition, the area is much greater. 
Practically it includes those parts of the skin to which the hind foot 
can be approximated. It commences posteriorly at the part which 
the hind leg can reach, generally 2 or 3 inches in front of the flank, 
though this will vary according to the size of the animal. It 
extends forwards to the shoulder, including the whole side of the 
animal, and even reaches up the side of the neck, and on to the 
root of the ear. The most sensitive portion is that part which in 
most dogs alone gives the reflex. 
The scratching area is very sharply defined. If in a sensitive 
animal the skin on the hack within half an inch of the middle line 
be scratched the leg of that side will move. If, however, the skin 
at a corresponding part of the opposite side be touched, the animal 
will scratch at once with the other leg. The same observations 
apply to the scratching areas when they extend ventrally to the 
middle line. The skin of the flank, of the muzzle, of the fore leg 
are outside this area, and outside the reach of the hind leg. They 
are scratched by the teeth or fore leg. As in the case of the pithed 
frog, if one side of the animal be scratched, and if the leg of that 
side be forcibly held, scratching movements of the opposite leg 
may often be observed. These movements may be observed in 
young puppies, and can readily be called forth in animals which are 
sound asleep. 
I have been unable to get these movements from cats, although 
the cat tribe is probably related to the dog tribe by common 
ancestry. In the rabbit, too, I have been unable to observe them. 
If, however, a guinea-pig be killed by a blow on the back of the 
neck, and if the skin at the side of the belly be gently tickled, the 
animal will bring the leg of that side rapidly to the part, and 
scratch it violently for some time. I have noticed, too, that after an 
ox has been killed by a blow of the pole-axe, the hind leg will be 
brought to the side of the body if that part be rubbed. The move- 
ment is similar to that made during life to get rid of flies. We see 
then that these reflex scratchings are sometimes present, sometimes 
absent in animals nearly related. This variation depends, no doubt, 
on the habits, but more especially upon the build of the animal 
itself. The cat possesses great mobility of the head and neck. It 
can lick its sides, and can reach most parts of its body with its fore 
