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of the nerve fibres are unprotected by any insulating covering. The 
researches of FLEcHSIG, as well as my own, have shown that these 
fine fibres are furnished with a thin layer of myeline nearly to 
their terminations, and beyond the medullary covering there is ap- 
parently a protective sheath of great tenuity, that is not readily 
recognisable by ordinary methods of staining, which the silver method 
does not show at all. It is therefore more than probable that it is 
only at the free bulbous termination of the nerve filaments that we 
have naked protoplasm, and from this uncovered nervous substance 
the dynamic forces generated in the corpora of the nerve cells are 
discharged by contiguity into the protoplasmic substance of other cells. 
Thus, in contradistinction to the hypothesis of CasaL, we have 
only comparatively few points at which the nervous forces may 
discharge themselves from axons to dendritic protoplasm, and these 
are situated at definite points on the terminal arborizations of the 
nerve filaments ; for, otherwise, what would be the necessity for a terminal 
apparatus, were the nerve conductors free to discharge their dynamic 
forces at any point at which they came into contact with the sub- 
stance of a dendron. The very close interlacing feltwork of dendrite 
and axon, especially in the outermost layer of the cortex, would alone 
necessitate some protective arrangement, for seated as the cells and 
fibres are, most closely packed together, nay in fact at times touching 
each other, the constant overflow of stimuli from cell to cell would 
be almost continuous. 
Granting that the ultimate fibrillae of the axons have a 
protective covering, we have still the protoplasm of the dendritic 
twigs unprotected from possible aberrant nerve excitations from 
the end-apparatus. But is this strictly true? Around the body 
of the cell we find an insulating mass of fluid, and as a capsule 
to the sac there appears a slight condensation of the tissue at this 
point that takes the place of a retaining membrane. This mem- 
brane apparently ends where the first of the gemmulae are thrown 
off from the ascending portion of the primordial process, and likewise 
at the location where the first buds appear on the basal dendrites. 
Does the insulating covering really end here? In absolute alcohol 
sections of the cortex of the cerebellum, taken horizontal to the 
surface and stained with anilines, particularly the blue-black, it is 
quite readily demonstrable that the fine membrane, which is now 
undoubtedly composed of fine glia threads, does not really cease 
but becomes attenuated, and continues to ascend and cover the 
protoplasmic prolongations of the cell. It would seem from this 
