154 JOURNAL OF COMPARATIVE NEUROLOGY. 
and WLAassAK, it is only necessary for me to accept the state- 
ments that the cones described by WyNN are not true neuro- 
keratin but a substance (either neucleoproteid or cerebrin) pre- 
cipitated along the walls of funnels, and as a consequence, to 
conclude that Wynn is dealing with some substance other than 
neurokeratin. As a consequence, Wynn failed to obtain the 
network structure of the neurokeratin. The results obtained 
by the Pat-WEIGERT technique are, however, extremely inter- 
esting, for the preparations stained by this method reveal the 
manner of distribution of the cerebrin (WLassaxk) which is com- 
plementary to that of the neurokeratin and thus indicate in- 
directly the distribution of the neurokeratin. 
The structure of the medullary sheath of the peripheral 
nerves, as revealed by these sections, seems to be as follows: 
The neurokeratin network which contains the myelin con- 
sists, first, of two thin layers, one beneath the primitive sheath, 
the other around the axis cylinder; these two layers are, how- 
ever, continuous at the nodes of RANVIER; second, of a chain 
of cones connected with both layers, the base of a cone being 
attached to the peripheral layer, the apex in the inner layer, 
each cone being made up of a continuous band of neurokeratin 
exhibiting meshes of variable size and converging from the 
primitive sheath to the axis cylinder. The clefts of Scumiprt- 
LANTERMANN occur at the situation of the cones, but in some 
cases they are also visible between the two cones.  Further- 
more, the cones present a great variability in number, size, and 
direction. These phenomena, just mentioned, may indicate 
that the Scumrpt-LANTERMANN clefts are produced artificially by 
rupture of the coagulated protoplasm along the walls of the 
cones. My own observations described above may advan- 
tageously be summarized as follows: 
(1) The peripheral nerve-sheath contains two layers of 
the neurokeratin, one beneath the primitive sheath and the 
other along the axis cylinder. These two layers are connected 
by bands of neurokeratin which run obliquely from the outer to 
the inner layer, thus presenting a funnel or a cone-shaped ap- 
pearance. 
