146 ‘ANTHROPOLOGY. | 
the body is developed only in certain situations where there is a correspond- 
ing refinement and development of sentient papille, which are enabled to 
take cognisance of these qualities with a wonderful degree of. nicety and 
perfection. ‘This power of tact, as it has been called, to distinguish it from 
mere touch, resides especially in the integuments of the fingers and toes. |. 
'. The office of the skin is not fulfilled merely by serving as an investment 
to the body, and as the seat of touch. It is the seat of an important secre- 
tion which serves to purify the blood in a manner somewhat analogous to 
respiration. This secretion is discharged a in the form of a fine vapor termed 
the ‘“insensible perspiration ;” but when the circulation is increased in 
activity, or when the body is exposed to a high degree of temperature, it is 
eiven forth in the form of minute drops, which appear like dewdrops upon 
the surface, and then becomes the ‘‘sensible perspiration” or “‘sweat.”” This 
exhalation carries off from the body a large quantity of water, carbonic acid, 
saline, and various animal or azotized matters, which are effete or injurious 
to the system. ‘The importance of a free escape for this cutaneous exhala- 
tion is well known. The skin is also the seat of a sebaceous or oily secretion, 
which preserves it in a soft or pliant state, repels external moisture, and 
defends it from the drying influence of the air. The skin is also an inhalant 
and absorbent surface, as shown by its numerous lymphatics arranged in a 
plexiform manner, and by the fact that immersion in water increases the 
weight and relieves the thirst. Nutritive substances have even been supplied 
to the body through the skin, and certain liquids applied to the surface 
have been subsequently detected in the urine. 
To fulfil all these important functions, we find in addition to the three 
essential elements, namely, the protecting epidermis, the chorion, and the 
areolar fibrous tissue, that there are superadded numerous glands and folli- 
‘cles, the sources of the perspiration and sebaceous secretion. There is also 
an extensive and minute capillary net-work of arteries, veins, lymphatics, 
and nerves. The latter are principally derived from the cerebro-spinal 
system; and so universally distributed are the vessels and nerves, that the 
smallest spot on the surface cannot be punctured with the finest instrument 
without the discharge of blood and the sensation of pain. There are also 
certain appendages to the skin, as the hair and nails, which will be con- 
sidered in their proper place. 
1. THe CUTICLE OR EPIDERMIS appears to be a thin, semi-transparent, 
grey lamina, hard, dry, horny, and homogeneous. When minutely examined, 
however, under water, its deep surface is found to be soft and moist, and 
numerous fine filaments may be seen to pass between it and the cutis vera. 
These are probably the elongated and ruptured extremities of the exhalant 
and sebaceous ducts, together with the sheaths of the fine nairs which 
invest almost its entire surface. The epidermis is composed of hard, dry 
lamine, in each of which may be observed one or two opake spots, the 
original nuclei and nucleoli of the cells, of a polygonal or irregular form, 
overlapping each other and adhering to subjacent softer scales. As the 
seales on the surface become more dry and thin they peel off, and pass 
‘away as particles of dust, or bran-like scales, as seen on rubbing the skin 
852 
