480 
THE NERVOUS SYSTEM OF MAN 
class is termed ‘lipoid.’ Its importance is immense. It is quite as 
important in the body as the nitrogenous or albuminous material 
which is present in every living tissue. It is very like fat in many 
respects,' but in other respects it is different. It contains nitrogen, 
which fats do not; it contains phosphorus, which fats do not; again 
it mixes with water, which, as is well known, fats do not. It has 
certain remarkable properties, in that it can make certain bodies 
soluble which are otherwise not soluble. 
“The walls of practically every living cell in the whole body are 
made chiefly of lipoid, and it is found that there are strands of this 
material running through and through the substance of every cell. 
In fact, there is no region of any cell in any part of the body that is 
without this material. 
“Perhaps the largest accumulation of lipoid is that in the nervous 
system. There is far more lipoid in the brain than in any other tissue. 
If you examine a nerve, or what physiologists call a nerve trunk, you 
will find that this nerve is composed of many thousands of nerve fibers, 
and each nerve fiber that conveys messages into or out of the brain is 
invested with an insulation jacket (similar to the insulation covering 
an electric wire) of lipoid and thus the stimuli are prevented from 
scattering. 
“It may be asked, ‘What has all this to do with alcohol?’ The 
connection is an important one, for only a few years ago two physio¬ 
logical investigators, — one with the English name of Overton, and the 
other with the distinctly German name of Hans Meyer, — without 
knowledge of each other’s work, discovered the principle that any 
substance that dissolved lipoid, or, what is the same thing, is dissolved 
in lipoid, is an anesthetic. Chloroform, ether, and all of these agents 
which are used in modern surgery to produce unconsciousness are 
dissolvers of lipoid. 
“Besides acting as anesthetics such substances act as poisons to 
every living thing in the body as well. The brain, owing to its high 
percentage of lipoid, is more sensitive to the action of chloroform than 
other organs of the body. 
“When chemists and physiologists found that lipoid was soluble in 
alcohol, it enabled them to rank alcohol as a narcotic poison, and it is 
now so classed. This statement is altogether irrespective of the effects 
it will produce on an animal.” Osborne. 
The question of brain efficiency is further illustrated by 
Figure 420. Long before birth the heart in the embryo 
begins to beat and is under the control of the nervous system. 
