88 
MAMMALIA. 
bat’s wing membrane consists of two sheets of skin, the upper de- 
rived from that of the back, the lower from that of the belly. The 
epidermic and Malpighian layers in each sheet remain separate, 
whilst the true skin is inseparably fused. In this fused medium 
layer are imbedded the muscles, nerves, vessels, etc., of the wing. 
The whole wing is covered, both on the upper and 
under surface, with extremely fine, sparsely scattered hairs. . . . 
Each hair sac has from two to seven sebaceous glands, according 
to the species, and one sweat gland opening into its sac. The two 
outer fibrous layers of the hair sac have no sharp line of demarca- 
tion to separate them from the surrounding connective tissue, but 
the inner or hyaline coat is highly developed, and, after being con- 
stricted beneath the hair bulb, widens out and encloses the sense- 
bodies (Tastkorperchen), one of which organs is connected with 
each hair. 
“ The nerves of the wings may be considered to consist of five 
layers, i. e., there is one occupying the centre of a transverse sec- 
tion of the wing, which gives off on each side of it four others, and 
these are successively finer and finer as they approach the opposite 
surfaces. The inner layer and the one immediately on each side 
of it, consist of nerve fibres with dark borders, the other layers of 
pale fibres only. The tastkorperchen are connected with the second 
layer. The fifth layer of finest fibres ends as a network between 
the innermost layer of cells of the Malpighian layer of the epidermis. 
The tastkorperchen are shaped like a fir-cone with a rounded apex 
turned inwards. They lie immediately below the root of the hair; 
and their core or central substance is formed of a prolongation of 
the cells forming the two root sheaths of the hair. Their length 
is 0.0259 and their breadth 0.0175mm. A nerve containing about 
six clark-edged fibres is distributed to each korperchen. Just 
before the nerve reaches this organ it splits into two, and three 
fibres pass to one side of it, three to the other. The fibres are 
then wound round the body so as to sheathe its cellular core. Dr. 
