684 The Relations of Mind and Matter. [July, 
this net work of protoplasm, which connects all the cells of many 
and possibly the active cells of all plants, may have a nervous 
function, though the conditions of plant life are such as seldom 
to call it into exercise. . 
In animals a similar structure has been observed in many cases, 
and particularly between epithelial cells, where it is most likely 
to be called into functional activity. Some observers claim that 
it is general, and that the animal body is an intricate net work of 
fibrill2, of which the cells forms the nodes. This doctrine, 
though it has been strongly combatted, is certainly not without 
considerable support in observation, and there is good reason to 
believe that such continuity of protoplasm exists between the 
cells of at least several of the animal tissues. 
Thus the primitive motor organism quite probably exists with 
‘little change throughout the highest animals, and may serve to 
bring every cell within the reach of motor influences, as the simi- 
larly minute vascular structure has a like result in regard to 
nutritive influences. The conditions here indicated, however, 
exist in very different degrees of perfection in different cells. In 
some tissues they may almost or quite have ceased to exist 
through lack of exercise. In nerve tissue, on the contrary, they 
are remarkably well developed. The large nerve cells of the 
ganglia possess an intricate fibrillar structure, so distinctly devel- 
oped that it was clearly recognized long before any one imagined 
that such a structure was a common feature of cells. And the 
extrusion of protoplasmic threads through the cell walls, in direct 
continuation of the internal fibrils, is equally well marked. The 
whole surface of some of the cells is covered with a series of fine 
nerve rootlets. Yet greatly developed as this structure is, there is 
no reason to doubt that it is a direct unfoldment of the general 
cell structure, with its nuclear and outer. cell fibrils and its one or 
more protoplasmic threads running to neighboring cells. In the 
case of nerve tissue the rootlets also connect with other cells, but 
the connected cells are often separated by very considerable inter- 
vals. Very likely this separation is a result of natural selection. 
In original Metazoa sensory impressions may have passed from 
‘cell to cell through the aid of their connecting protoplasmic 
_ threads. In forms in which no nerves can be discovered this 
_ ‘method _ still continue, as a slow yet sufficient process. But 
nal life developed the connected cells seem to have become 
