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XVIII. On the Powers on which the Functions of Life in the more perfect Animals 
depend, and on the Manner in which they are associated in the production of their 
more complicated results. By A. P. W. Philip, M.D. F.R.S. L. &; E. fyc. 
Received May 29, — Read June 16, 1836. 
In considering' the powers of life, I shall in the first place inquire into the 
seat, the functions and the nature of each of these powers ; and then point out 
the manner in which they are associated in the production of their more complicated 
results *. 
OF the powers of the living animal the simplest is that by which the motion of its 
various members is effected, and which essentially contributes to all its more com- 
plicated functions, the contractile power of the muscular fibre, the healthy action of 
which is not a state of uniform contraction but of a constant and generally rapid suc- 
* The following paper comprehends the results of a task, not of a few months or years, but, with the ex- 
ception of the time devoted to the more active duties of my profession, of the greater part of not a short life. 
As far as I can, to render what I have done useful, it is necessary that the various facts should be com- 
pared, and thus the inferences they afford ascertained. They are dispersed through so many publications, 
eleven papers in the Philosophical Transactions, published in the course of twenty years, an Inquiry into the 
Laws of the Vital Functions, a Treatise on the Influence of Minute Doses of Mercury in restoring the Func- 
tions of Health, my Gulstonian Lectures on the more obscure affections of the Brain, &c., that although they 
are frequently referred to, it has almost always been, more or less, under mistaken views ; because the 
writer, in commenting on one part, has been unacquainted with others with which it is intimately con- 
nected, for in so protracted an investigation, few will take the trouble to keep pace with the inquirer. 
It will appear from the references in the following paper how each of the various facts, dispersed through 
so many publications, has contributed to fill up the great outline of the laws that regulate the animal func- 
tions, which has been the object of my labours, and from which the topics of the day have never induced me to 
swerve. It is evident that this outline must be ascertained, before the functions of particular organs can be 
successfully investigated ; all of which more or less depend on the general laws of our frame. 
The following I believe is the first attempt which has been made to ascertain experimentally the seat, the 
functions and the nature of all the powers of the more perfect animal, and the various relations they bear to 
each other, by which, several and in some functions all of these powers being enabled to cooperate, their more 
complicated results are effected. In the latter part of the subject, I have found much care required in ren- 
dering the language sufficiently explicit ; and if in any instance I have failed in this attempt, I hope it will in 
some degree be ascribed to the very complicated nature of the subject, arising from the great variety of facts 
on which the conclusions are necessarily founded. 
It will be admitted with respect to the conclusions themselves, that the circumstance of the present inquiry 
embracing the whole of the subject is in favour of their accuracy ; because in that case, and where, as in the 
present instance, all the parts are intimately connected, few inferences consequently resting on any single 
position, an error may betray itself in so many ways, that it can hardly escape detection. 
