INNERVATION OF INTEGUMENT OF CHIROPTERA 333 



and foniiiiig the second nerve layer. Arising from the latter are 

 medullated fibers which pass to the stratum JVIalpighii. Here 

 they divide, forming a simple, non-medullated network, which 

 constitutes the third nerve layer. 



2. Certain regions of the flying and interfemoral membranes 

 have three layers of nerves, others but two. These are (1) A 

 layer of medullated nerve trunks with numerous medullated 

 branches, occurring in the stratum reticulare, but only in the 

 elongated ridges containing the largest blood vessels and much 

 connective tissue; (2) A double, medullated nerve layer in the 

 deeper part of the corium extending throughout the membranes; 

 (3) a layer, likewise double, present in the entire Malpighian 

 stratum, and consisting of a large number of branching non- 

 medullated nerve fibrils. 



3. Numerous varicosities are found in the corium on branches 

 from the second nerve layer. 



NERVE ENDINGS IN THE INTEGUMENT 



1. Free nerve terminations occur in the uMalpighian layer. 

 Small medullated fibers from the third nerve layer can be 

 traced out among the deeper Malpighian cells to the stratum 

 granulosum, where they terminate in minute end-knobs, probably 

 intercellularly. 



2. Nerve fibers supplying the hair follicles may be distributed 

 in two ways: (a) The whole fiber may end directly in a single 

 follicle; (b) On approaching hairs a fiber may divide, one or two 

 branches going to a follicle and the others passing out to the 

 epidermis. 



3. Nerves end on pelage hairs at three levels and in three differ- 

 ent sheaths of the follicles. These endings are: (1) A super- 

 ficial nerve ring situated above the orifices of the sebaceous 

 glands, and giving off nerve threads in the connective tissue 

 sheath; (2) fine, varicose or flattened nerve fibrils which lie im- 

 mediately below the sebaceous glands, and terminate on the hy- 

 aline membrane parallel to the long axis of the hair; (3) Nerve 

 fibrils at the level of the lower third of the follicle, which usually 

 take a horizontal position in the outer root sheath. 



JOUKNAL OF MORPHOLOGY, VOL. 25, NO. 2 



