260 
arrangement as if it was probable that the cells of the cortex are 
likewise furnished with an enveloping membrane. We consider there- 
fore that the fine stem of the gemmule, at the point of branching from 
the dendritic stem, penetrates through an enveloping sheath, and it 
is accordingly only at the tips of the gemmules that we have actually 
free dendritic protoplasm. Thus it is only at the nearest point to 
that in which it is conceivable for the impulse from the end-ramuscules 
of the nerve fibre to come into contiguity with the free cellular 
protoplasm, that we find uncovered cellular substance. 
This theory is in entire concordance with the anatomical structure 
of the part, and accounts for the fact that the twigs of the dendrites 
and the fibres touch each other frequently, and in a manner that 
appears to be perfectly indifferent for the different kinds of nervous 
substance, receptive and projective. | 
The silver phospho-molybdate method !) usually stains with great 
distinctness the end-apparatus of the nerve fibres having their origin 
both intrinsic and extrinsic to the cortex; the only ones remaining 
insufficiently impregnated are those belonging to the peculiar cells of 
the molecular layer. So far as the end-apparatus of the collaterals 
from the pyramidal cells of all kinds are concerned, the terminations 
of the intermediary cells, the fibres entering from the medullated 
masses, all have the same end-apparatus, which consists solely of a 
simple, freely-ending bulbous termination situated upon the extremity 
of the finest branches of the nerve fibres. With the collaterals of the 
pyramidal cells, and the axons of the intermediary, especially the 
pluripolar ones, the method of terminating can be very distinctly and 
definitely be determined. With the terminations of the association 
fibres it is equally distinct, but the difficulties of ascertaining to which 
class the fibre belongs is greatly increased by the length of the tra- 
jecture through the layers of the brain-rind, and indeed were it not 
for certain characteristic differences between the terminal apparatus 
of intrinsic and extrinsic fibres, it would be most difficult to determine 
where the latter belonged, as it is almost impossible to follow the 
extrinsic fibres, owing to their sinuosities and length, through the 
entire thickness of the cortex. 
The difference between the two kinds of fibres consists entirely 
in the final disposition of the terminal ramifications of the colla- 
terals from the association, ascending fibres, and those from the axons 
of the psychical and other local cells. 
1) Brain, 1896, Winter Number, 
