PIGMENT. 
209 
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ceous follicles on either side ; many of these follicles 
are enormously dilated, and within them a quantity of 
dark granular matter is contained, thus affording a 
good example of one of the forms of the disease called 
acne, which essentially consists of an enlargement and 
suppuration of the sebaceous follicles. The colour of 
the hair frequently depends upon the pigment developed 
in the cuticle ; and it is a well-known fact, that in those 
animals, as the Pig, in which there are occasional 
patches of black hair, the skin from which such hairs 
grow is generally black; so, in the Albino, the hairs 
are white, because no pigment is secreted. 
Pigment is developed in peculiar situations under 
certain circumstances, as around the nipple during preg- 
nancy, and in certain spots on the face, called freckles, 
after exposure to a summer’s sun ; in both these in- 
stances the colouring matter disappears on the removal 
of the exciting cause. Pigment is secreted by the 
Cuttle-fish in a special gland, termed the ink-bag, 
and this pigment is largely employed by the artist, 
under the name of sepia. Pigment is also secreted 
in cells in certain states of disease, as in melanosis — 
a striking specimen of which in both ovaries of a 
female is preserved in the Museum. In the lung of 
a Calf, here and there, a lobule is quite black, whilst 
all the others are perfectly white. A section of one 
of these black lobules, demonstrates that the pigmental 
matter is deposited in the form of irregular granules 
in the parenchyma of the lung, and such lobules 
p 
