vented from doing its proper work 
other organs try to carry it on, and the 
result is that those organs which are 
really beyond our control, and which 
will work properly without any atten- 
tion from us, become diseased by our 
bad treatment of the organ that comes 
first in the natural order of attention. 
The skin throws off waste matter 
from the system. Two and one-half 
pounds of watery vapor is poured out 
daily from the average man. A clogged 
skin retains certain salts in the system 
supposed to have something to do with 
such diseases as rheumatism and gout 
if left in the blood by two little exer- 
cise of perspiration. 
Besides the sweat glands there are 
glands which exude fatty substances 
upon the skin, keeping it suitably lubri- 
cated and somewhat impervious to water. 
In some animals this secretion is soabun- 
dant that the skin cannot become wet 
in swimming. Beneath the skin are 
frequently cushions of fat to protect the 
soles of the feet and the outside of the 
larger joints. The blubber of the whale, 
the thickest skinned of all animals, is of 
this sort, and is evidently intended to 
make his tremendous weight less de- 
structive when brought in contact with 
other objects. The hide of the swifter 
ones is peculiarly fitted with large pa- 
pillae of feeling which are supposed to 
warn them of the presence of rocks and 
other objects by the action of the water 
while swimming near them. 
Insects, not having lungs, receive air 
into their bodies through holes in the 
skin. These are called spiracles. They 
are so protected by hairs within the 
holes that water will not enter them. 
This is why it is so difficult to drown 
an insect. But if you touch the abdo- 
men of one of these skin-breathing 
creatures, for instance the yellow part 
of a wasp, with a drop of oil, the 
minute openings become almost imme- 
diately clogged and the insect falls 
dead as if choked completely. 
The skin consists of two layers, both 
of which are exceedingly interesting. 
The outer or scarf skin is called the 
cuticle on the outside of the body, 
while wherever the skin dips into the 
body it is modified into what is called 
mucous membrane. This outer skin is 
not what is rubbed off the surface in a 
Turkish bath manipulation or what is 
brought off by the rubbing one gives 
the body with a rough towel. These 
rubbings bring off merely the dead 
outer surface of the cuticle which 
should be out of the way because no 
longer useful. In man it continually 
wears off, in serpents it is shed annually 
in one slough. 
The cuticle is the portion of the cov- 
ering of the body which may best be 
noticed when a blister has been raised 
in the skin. The blister is an accumula- 
tion of fluid between the cuticle and 
the true skin. 
The cuticle, or epidermis, is modified 
in many other ways than the one in 
which it becomes mucous membrane. 
Where the habits of the animal make 
warmth desirable the epidermis dips 
into the skin and without any break in 
its connection rises in the form of 
wool, which covers the body of the 
sheep so effectually. Where the ani- 
mal is designed for flight there is the 
same characteristic dip into the ma- 
terial of the body, and out of the little 
sac so formed rises the feather which 
gives the bird its beauty and powers of 
flight. The feather is a modification of 
the scarf skin. 
Where protection is needed for the 
body beneath the surface of the water 
this changeable substance covers the 
true skin with hard scales that make 
the friction of the water as slight as 
possible, while giving a firm and light 
resisting surface to prevent wounds. 
Horns and hoofs are modifications of 
the scarf skin. Where claws or talons 
are needed in the business of fighting 
or tearing food in bits or digging holes 
in the ground or elsewhere, the scarf 
skin changes itself at the extremities 
of paws and feet and produces nails, 
talons, and claws, whose powers are 
both marvelous and varied. For the 
protection of most mammals the whole 
of the body is favored by this power of 
the scarf skin to produce whatrver 
seems necessary for the comfort of the 
individual, and the body is indented 
with innumerable minute holes called 
hair follicles into which the scarf skin 
dips and rises again to the surface 
transformed into hairs of varying de- 
138 
