252 University of California Publications. [zoology 



are shown running for Long distances beneath the corium, and 

 branches can even be seen to turn toward the epidermis, but all 

 traces of them are lost as soon as they enter the corium. 



The other method of Mallory gives like results as far as the 

 distribution of the nerves beneath the corium is concerned. In 

 cross sections of the tail it is often possible to trace a fibre from 

 the roots leaving the cord out to the corium. Sometimes this 

 may be seen in one section: in many cases two or three neigh- 

 boring serial sections will show the same. The plexus beneal h 

 the corium is shown best, as a whole, in frontal sections of the 

 tail. Here it will be seen that the nerves arc very numerous, and 

 with the method in hand can be traced to their connections with 

 the cord. There can be no question as to the presence of the 

 nerve-bundle layer of the plexus that Herrick and his pupils have 

 shown: but as regards the stratum of glanglion cells, it seems 

 to me that Schubert's criticism holds good. At any rate neither 

 of Mallory's methods reveals such a structure, and this would at 

 least seem strange in view of the beautiful staining of other nerv- 

 ous elements. In cross sections of the tail, Mallory's fuchsin 

 method shows nerves running in or immediately beneath the 

 inner corium layer. At times several fibres are in view at once, 

 being, however, of different sizes. 



Within the corium the distribution of the nerves to the glands 

 is not apparent in sections which pass through the gland, owing 

 to the exceedingly small size of the fibres. But when the peri- 

 phery of the gland is just denuded, the nervous elements are 

 shown very clearly. In such cases it will be seen that there is a 

 feltwork of many verg fine fibres closely investing the gland, end- 

 ing upon tin' muscle fibres and around the nuclei of the gland cells. 



The endings upon the muscles are shown both by Cajal's 

 method and Mallory's fuchsin stain, and in some cases are typi- 

 cal (PI. XXII, Pigs. 25 and -t>) as described by Huber and 

 Dewitt ('97) and Coghill ('99). That is, they are equipped with 

 terminal expansions or bulbs which lie on the muscles. In many 

 cases line branching fibres can he clearly seen lying upon the 

 muscle laser. These pass over ultimately into the finest of 

 slender twigs which without terminal expansions always lie on a 

 muscle abre and end there (PI. XXII, Fig. 26.) 



