94 TISSUES OF THE NERVOUS SYSTEBC 



horizontal branches, or with processes of the deeply stained 

 branched cells above described. Isolated fibres may be traced 

 in the rete Malpighii to within a short distance of the horny 

 layer, where they either seem to lose themselves in swellings 

 of various size, or to divide dichotomously beyond ; eventually 

 returning towards the corium. The hair bulbs are also sur- 

 rounded by a network of fine non-medullated nerve fibres, the 

 further description of which will be found in another part. 



Nerves of the Tadpole's Tail. The best object for the 

 purpose is the tadpole of Hyla. The distribution to be now 

 described may be studied in recent preparations in half per 

 cent, salt solution or serum. It is, however, better to make 

 preparations by the method fully described in the chapter on 

 connective tissue. The peripheral nerves of the tadpole's tail 

 are derived from a plexus which lies immediately underneath 

 the sub-epithelial hyaline layer; the nerves which form it are 

 composed almost entirely of non-medullated fibres, which are 

 invested in a sheath beset with oblong nuclei. From this plex- 

 us similar fibres arise towards the epithelium, and by division 

 become smaller and smaller, anastomosing with each other 

 so as to form a second plexus nearer the epithelium than the 

 other. They also possess nuclei, the position of which in re- 

 lation to the fibre is sometimes lateral, sometimes apparently 

 axial. In the more superficial plexus, spindle-shaped enlarge- 

 ments are frequently seen at equal distances from each other. 

 These are distinctly granular, and each contains one oblong, 

 clear, sharply-defined nucleus, and nucleoli. They are to be 

 considered as bipolar ganglion cells, occurring in the course 

 of the fine non-medullated fibres. Immediately under the epi- 

 thelium the densest branching of the fine, pale fibres is seen. 

 These bifurcate repeatedly, displaying at tolerably regular dis- 

 tances, and especially at the points of division, numerous 

 granular swellings. The branchlets arising from this repeated 

 division join each other archwise, forming a very close network, 

 the meshes of which are round, or more often polyhedral, and 

 of such size that two or four of them can be covered by the 

 nucleus of an epithelial cell. In this network, nuclei and cells 

 are scattered, the former being sharply defined and of oblong 

 or irregular shape, exactly similar to those mentioned above 

 as occurring in the fine non-medullated fibres. The cells are 

 spindle- or (more frequently) star-shaped, flat, and finely granu- 

 lar, each containing a roundish nucleus. Their short pointed 

 processes are in continuity with the fibres of the nerve plexus. 

 They may be regarded as multipolar ganglion cells. (See p. 

 77, u peripheral nerve cells.") I could never find any connec- 

 tion between the pale nerve fibres and the well-known pale or 

 pigmented branched cells of the connective tissue. From 

 these facts we learn that the fine nerves of the tadpole's tail 



