term it, is four-fold in structure.  Proceeding downwards, we have—­(first) the outer skin, scarf-skin or cuticle; (second) a second layer or skin called the rete mucosum, forming the epidermis; (third) papillary layer; (fourth) the corium layer, forming the dermis.  The peculiar, globular, cellular masses below in the corium are called adipose cells, and these throw off perspiration or moisture, which is carried away to the surface by the glands shown (called sudoriparous glands), which, as is seen, pass independently off to the surface.  Other glands terminate under the skin in the hair follicles, which follicles or hair sockets contain or enclose the hair roots.  These glands terminating in the hair follicles secrete an oily substance, which bathes and lubricates as well as nourishes the hair.  With respect to the origin of the hair or wool fibre, this is formed inside the follicle by the exuding therefrom of a plastic liquid or lymph; this latter gradually becomes granular, and is then formed into cells, which, as the growth proceeds, are elongated into fibres, which form the central portion of the hair.  Just as with the trunk of a tree, we have an outer dense portion, the bark, an inner less dense and more cellular layer, and an inmost portion which is most cellular and porous; so with a hair, the central portion is loose and porous, the outer more and more dense.  On glancing at the figure (Fig. 6) of the longitudinal section of a human hair, we see first the outer portion, like the bark of a tree, consisting of a dense sheath of flattened scales, then comes an inner lining of closely-packed fibrous cells, and frequently an inner well-marked central bundle of larger and rounder cells, forming a medullary axis.  The transverse section (Fig. 7) shows this exceedingly well.  The end of a hair is generally pointed, sometimes filamentous.  The lower extremity is larger than the shaft, and terminates in a conical bulb, or mass of cells, which forms the root of the hair.  In the next figure (Fig. 8) we are supposed to have separated these cells, and above, (a), we see some of the cells from the central pith or medulla, and fat globules; between, (b), some of the intermediate elongated or angular cells; and below, (c), two flattened, compressed, structureless, and horny scales from the outer portion of the hair.  Now these latter flattened scales are of great importance.  Their character and mode of connection with the stratum, or cortical substance, below, not only make all the difference between wool and hair, but also determine the extent and degree of that peculiar property of interlocking of the hairs known as felting.  Let us now again look at a human hair.  The light was reflected from this hair as it lay under the microscope, and now we see the reason of the saw-like edge in the longitudinal section, for just as the tiles lie on the roof of a house, or the scales on the back of a fish, so the whole surface of the hair is externally coated with a firmly adhering layer of flat overlying