of Edinburgh, Session 1885 - 86 . 
659 
The difference between wool and hair is rather one of degree than 
of kind, and all the wool-bearing animals have the tendency when 
their cultivation is neglected to produce hair rather than wool, in 
the same way that cultivated cotton wTien neglected reverts to the 
original type of wild cotton, and the fibres lose their spiral character, 
which is of such value in the process of spinning. This tendency 
also always manifests itself whenever the conditions of soil and 
climate are unfavourable to the fullest development of the animal, 
and many sheep and other allied animals therefore produce both 
wool and hair ; the fine hair in many animals being very like wool, 
and the coarse wool in others closely resembling hair. 
The true difference does not consist, as is generally supposed, in the 
fact, that wool possesses a waved or curled structure in the fibre which 
is absent in the case of many hairs, but in the method of attachment 
of the epidermal scales which form the external covering of the fibre. 
The curled locks of the negro consist of true hair and not wool, 
and there are many cases in the lower animals where the structure of 
the fibre is that of a true wool, while the straightness and want of 
curl usually associated with the hair is still retained. 
The general structural peculiarities which distinguish them from 
other epidermal growths, are however the same both in wool and 
hair, and the method of generation is the same in both cases, so that 
a description of the one will also serve for the other, with such 
variation as will be pointed out later on. 
Hairs are true appendages of the skin, being outgrowths of the 
epidermis. When attached to the animal each hair is implanted in 
a cutaneous depression, which is an involution of the skin, forming 
the hair follicle. In structure the walls of this follicle consist of 
layers, derived from the epidermis and from the cutis vera. The 
hair is fixed into this follicle and attached to the bottom by a dila- 
tion called the knob or bulb of the hair which encloses the papilla, 
or pulp, and is in living connection with the fibrous sheath of the 
follicle. The papilla or pulp belongs to the follicle rather than the 
hair, and corresponds to a papilla of the skin. It is rounded or 
oval in shape, consisting of distinctly fibrous areolar tissue, with 
nuclei and fat granules, but without any cellular structure, and is 
attached to the fibrous coat of the base of the follicle by a cylindrical 
portion or stalk. 
