476 ANIMAL PHYSIOLOGY. 
the occasion a man may in a boat-race originate muscular con- 
tractions that he could not by the strongest efforts of his will 
call forth under other circumstances. Such are always dan- 
gerous. We might speak of a reserve or residual nerve force, 
the expenditure of which results in serious disability. It also 
applies to mental and emotional effects as well as muscular, 
and seems to us to throw light upon many of the failures and 
successes (so called) of life. 
It seems that our past views of secretion and nutrition have 
been partial rather than erroneous in themselves, and it is a 
question whether it would not be well to substitute some other 
terms for them, or at least to recognize them more clearly as 
phases of a universal metabolism. "We appear to be warranted 
in making a wider generalization. To regard processes con- 
cerned in building up a tissue as apart from those that are rec- 
ognized as constituting its function, seems, with the knowledge 
we at present possess, to be illogical and unwise. Whether, 
in the course of evolution, certain nerves, or, as seems more 
likely, certain nerve-fibers in the body of nerve-trunks, have 
become the medium of impulses that are restricted to regulat- 
ing certain phases of metabolism—as, e. g., expulsion of formed 
products in gland-cells—is not, froma general point of view, 
improbable, and is a fitting subject for further investigation. 
But it will be seen that we should regard all nerves as “ tro- 
phic” in the wider sense. What is most needed, apparently, isa 
more just estimation of the relative parts played by blood and 
blood-pressure, and the direct influence of the nervous system 
on the life-work of tne cell. These views are greatly strength- 
ened by the facts, well known to every observer of disease in 
the human subject. The preponderating development of the 
cerebrum in man must be taken into account in the working 
of every organ. To have a healthy stomach, liver, kidneys, 
etc., is not enough ; for real health, all the parts of that great 
complex of organs we call the brain must not only work, but 
work in concert. 
We must regard the nervous centers as the source of cease- 
less pulses that operate upon all parts, originating and con- 
trolling the entire metabolism, of which what we term func- 
tions are but certain phases, parts of a whole, but essential for 
the health or normal condition of the tissues. Against such a 
view we know no facts, either of the healthy or disordered or- 
ganism, 
Summary of Metabolism.—Very briefly, and somewhat incom- 
