1885.] The Relations of Mind and Matter. 687 
primitive connected-cell conduction. All these cells did not dis- 
appear or suffer conversion. Some were retained, perhaps as cen- 
ters of distribution, by whose aid a single inflowing current could 
be sent off in several directions as a partial survival of the origi- 
nal general distribution. And significantly, near these cells the 
axis cylinder is naked. The cell matter has not been converted 
into a medullary sheath. Yet more significant indications of 
such an origin of the nerve system are seen in the bipolar nerve 
cells. In these a nerve fiber enters the cell on each side, and its 
fibrillated structure is clearly continuous with the fibrillæ of the 
cell. And in many cases the medulla of the fibers is continued 
over the cell. Such a cell, therefore, appears to be a survival of 
the primitive nerve, and indicates its origin, as above conjectured, 
from a line of cells with protoplasmic fibrillar connections, - 
There is one more point here to consider, that of the termini 
of the nerve fibers, It is quite probable that they never terminate 
in the ganglionic cells, not even in those of the cerebrum, but that 
they connect with the fibrillæ of these cells, which in their turn 
connect with outgoing fibers. Nor is it by any means sure that 
they have actual termini in the peripheral and muscular cells. 
- Indications point to the contrary. In many cases they seem to 
pass continuously through these cells and rejoin the exterior 
nerve fibrils, or to end ina plexus whose fibrille are probably 
‘continuous. Thus in the highest development of nervous tissue 
there is singularly little change in structure from the condition 
of undifferentiated cell tissue. 
We may look upon the function of the nerve fibers as simply 
conductive, though it is possible that they add to the strength of 
the motor current through chemical change which takes place in 
their tissue. What is the function of the nerve cells? Very 
probably their action resembles that of the electric resistance 
coil. In telegraphy by decreasing the diameter of the wire the 
passage of the current is resisted, and part of it loses its electric 
character. By suitable contrivances this checked current may be 
converted into heat, light, magnetism or other forms of force. In 
the nerve cells the minute fibrillæ over which the current must 
pass seem to have a similar function. Part of the motor energy 
is converted into some other form of force. It may become heat. 
It may outflow into the high-atomed muscle molecules and cause 
chemical change. Or it may assume some other condition, as it 
