LANCASHIRE VETERINARY MEDICAL ASSOCIATION, 43 
And the education of this sense, effected by concentration of 
attention and increased powers of appreciation and adaptation, 
enables the blind to read with their fingers, to trace the most minute 
variation of form or surface, and even to detect the mysterious 
tactile differences of colours. 
The sensibility of the skin varies in different parts of the body. 
Thus, it is the greatest on the tips of the fingers, and least in the 
middle of the limbs. This is practically illustrated by taking hot 
water, and immersing the finger of one hand and the centre of the 
other hand. The single finger will suffer no inconvenience from the 
heat, while to the other hand it may be insupportable. For the 
same reason the hand is better adapted than the finger to test the 
temperature of a bath before the immersion of the body, and even 
then it may be found that a heat which is pleasant to the hand may 
be intolerable to the entire skin. 
The sensibility of the skin is subject to considerable modification 
under the influence of disease. The natural sensibility may be 
heightened, or it may be diminished, or, again, it may be altered. 
These changes obviously depend on some modification of the nervous 
system, the nature of which is, for the present, at least, beyond our 
grasp. 
The more common morbid sensations of the skin, in addition to 
heat and cold, are itching, tingling, smarting, pricking, shooting, 
creeping, tickling, burning, scalding, &c., and it is to be remarked 
that these sensations are more acute in certain situations than in 
others, and that they are simple modifications of common sensation, 
and have no connexion with the special tactile function of the skin. 
By means of its absorbing power the skin is enabled to act as a 
respiratory organ. The process of absorption in the skin is effected 
by an active endosmosis. This function ot the skin is calculated 
to enact an important part in the health of the animal, in relation 
to the purity or the impurity of the atmosphere in which it moves. 
I have known cases where animals have been destroyed from the 
incautious use of mercurial ointment, which has become absorbed 
into the system, and produced a fatal effect. 
The softness and pliancy of the skin are, in a great measure, de¬ 
pendent on the secretion of the sebaceous substance which is poured 
out on every part of the surface of the body. 
The function of the skin as a regulator of the temperature of the 
body and as a purifier of the blood is effected by means of a peculiar 
secretion—the perspiration. 'W^hen this secretion is eliminated in 
form of an imperceptible vapour it is termed insensible, and 
when condensed or poured out in a fluid state sensible, perspiration. 
The insensible perspiration is partly derived from the sudoriparous 
and sebiparous glands, and partly from the natural evaporation 
taking place from the epidermis. 
The quantity of perspiration is altered by a variety of circum- 
stances which affect the body physically, or tlirough the agency of 
the nervous system. Of the former kind are the temperature, cur¬ 
rent and hygometric condition of the atmosphere, and stimulation 
