300 Canadian Record of Science. 
now know that this nerve contains fibres which have a 
diverse action on the metabolism of the heart, and that ac- 
cording as the one or the other set is stimulated, so does 
the electrical condition vary; and everywhere, so far as 
known, a difference in electrical condition seems to be as- 
sociated with a difference in metabolism, which may be one 
of degree only, perhaps, in many instances, still a differ- 
ence. The facts, as brought to light by experimental stim- 
ulation, harmonize with the facts of degeneration ,by the 
cardiac tissue on section of the vagi; but this is only clear 
on the view we are now presenting that the action of the 
nervous system is not only universal, but that it is constant ; 
that function is not an isolated and independent condition 
of an organ or tissue, but a part of a long series of meta- 
bolic changes. It is true that one or more of such changes 
may be arrested just as all of them may go on at a lessrate, 
thus, actual outpouring of pancreatic secretion is not con- 
stant; but secretion is not summed up in discharge merely, 
and on the other hand it would seem that in some animals 
the granules of the digestive glands are being renewed 
while they are being used up in secreting cells. The pro- 
cesses may be simultaneous or successive. Nor do we wish 
to imply that the nervous system merely holds in check, or, 
in a very general sense, co-ordinates processes that go on 
unoriginated by it. We think the facts warrant the view 
that they are in the highest mammals, either directly (most) 
or indirectly originated by it; that they would not take 
place in the absence of this constant nervous influence. 
The facts of common observation, as well as the facts of 
disease, point in the strongest way to such a conclusion. 
Everyone has experienced the influence on, not one, but 
many, functions of the body, we might say the entire meta- 
bolism of depressing or exalting emotions. The failure of 
appetite, loss of flesh and mental power under the influence 
of grief or worry, tell a plain story. Such broad facts are 
of infinitely more value in settling such a question as that 
now discussed than any single experiment. 
The best test of any theory is the extent to which it will 
