244 Growth and Histogenesis of Nerves 
which give rise to true plexuses by the anastomosis of long, narrow 
branches which extend outward from the cell-body in various directions. 
Four such plexuses may be distinguished: a deep one in the corium, a 
middle and a subepithelial in the papillary layer, and an intra-epithelial. 
The Remak nerves of Type II likewise are composed of anastomosing 
cells which give rise to a true plexus. The protoplasm of the processes of 
these cells, however, is much more developed than in those of Type I, 
and there seems to be much less branching of the processes. Often the 
protoplasm of these cells shows a distinct fibrillation. Certain cells 
seem to be in a state of transition between Type I and Type II. The 
medullary nerves terminate in arborizations, telodendrites, in which 
plexus formation is shght or does not exist. The ramifications of the 
medullary nerves may resemble the Remak fibres for a distance, or they 
may at once pass over into naked processes which are marked by plate- 
like varicosities and terminate either “‘ free” or in sense-organs. Leon- 
towitsch thinks that there is constant physiological regeneration going 
on in the skin and that this takes place by a transformation of the 
“ Remak ” cell-plexuses into the peripheral portion of the “ neurite ” of 
the central ganglion cell. He can explain his findings only on the hy- 
pothesis advanced by Schwann, Balfour, and numerous recent investi- 
gators that the nerves arise by differentiation from a chain of anasto- 
mosing cells. 
Although Leontowitsch makes the statement that the tyro can distin- 
gush between connective-tissue cells and the cells he figures as belong- 
ing to Remak nerves Type I, I do not think that he makes the distine- 
tion clear either in his text or figures. The cells of the Remak nerves 
Tvpe II may well be taken for sheath-cells surrounding small bundles 
of fibrils such as are known to exist in the sympathetic system, the intes- 
tinal plexuses, and in the whole peripheral nervous system during early 
embryonic development. Gold-chloride and methylene blue both show 
an affinity for the sheath-cells as well as for the nerve-fibrils. Although 
T have not had an opportunity to repeat Leontowitsch’s work exten- 
sively, my own studies on the nerves of the skin lead me to believe that 
there is nothing there to disprove the hypothesis that the sensory nerves 
of the skin are developed from nerve-fibrils which have grown out from 
central ganglion cells and which multiply greatly in number by branch- 
ing. The growing fibrils are closely accompanied by sheath-cels until 
near their ultimate termination. The ensheathed paths, but not the 
contained fibrils, may either anastomose freely or to no considerable 
extent, according to the region in which the branching takes place. 
Galeoti and Levi in a recent valuable contribution have described 
