564. A. B. DAWSON 
INNERVATION 
In the study of the nerves of the skin of Necturus the best 
results were obtained from the pyridin-silver nitrate-pyrogallic 
acid method of Ranson. This method does not affect the sheaths 
of the nerves, but when successful leaves the axis cylinders black. 
In the subcutaneous connective tissue the nerves form a 
wide-meshed plexus. From this small bundles pass outward, 
some going to the glands, others continuing to the epidermis. 
No evidence was found of the presence of a stratum of nerve cells, 
such as Herrick and Coghill (’98) and Coghill (99) have shown. 
Esterly (04) found in Plethodon nerve fibers running for 
long distances beneath the dermis, and in many places they could 
even be seen to turn toward the epidermis, but all trace of them 
was lost as soon as they entered the dermis. 
In Necturus small bundles can be readily followed through the 
dermis, but they can seldom be traced directly into the epidermis. 
This is due, in many cases, to the fibers’ turning at right angles 
at the outer surface of the dermis and running for some distance 
parallel to the surface of the body before turning outward into 
the epidermis. Within the epidermis nothing but free inter- 
cellular fibers were found. These were seldom branched and 
were never found to terminate in small knobs or plates such as 
have been described for the epidermal fibers of many Amphibia. 
Owing to the fineness of the fibers, the distribution of the 
nerves to the glands is not very apparent. This is especially 
true in sections passing through the median portions of the gland. 
However, in sections perpendieular to the surface of the body 
cutting the glands tangentially and exposing the surface of their 
walls, the nervous elements are easily distinguished. In no case 
was there found a network of fine fibers closely investing the 
gland, but at frequent intervals small bundles, usually consisting 
of from four to six nerve fibers, were seen leaving the nerve 
plexus below and coming toward the glands. In those of the 
mucous type these nerve fibers spread out over the outer surfaces 
of the gland cells and branch only occasionally. No evidence 
of intra- or intercellular endings was obtained. 
