178 DR ALISON’S OBSERVATIONS ON 
ence of the action of which, at these points, is determined by no other condition, 
that we can see, than their position. 
This mode of limitation of the vital affinities by which the selection and ap- 
propriation of living matter is effected, is only a statement of fact, and the most 
general fact that has been ascertained; and it seems highly probable, that it will be 
found an ultimate fact, in this department of science. It may serve to familiarize 
our minds with this principle to observe, jirst, that it is precisely analogous to 
the principle which is now well established as a first truth in the physiology of 
the nervous system, that portions of nervous matter, precisely similar in structure 
and composition, have perfectly different endowments according to the anato- 
mical position which they occupy; and, secondly, that the same principle seems 
distinctly exemplified in various cases of diseased action. The phenomena of 
inflammation, and especially the easy recurrence of inflammation once excited 
at any one spot in a living animal, indicate that certain vital attractions and 
affinities existing among the particles of the blood, and between them and the 
surrounding textures, are peculiarly modified, not merely in a particular manner, 
but exclusively at a particular spot. From the spot where it commences (e. g., 
on a serous membrane), this alteration of vital actions extends, as from a centre, 
to parts that are contiguous to, although having no vascular connection with, 
that where it commenced, as we see in tracing it from one fold of the peritoneum 
to another. And when we examine the results of the inflammation in the dead 
body, we see what clearly shews the operation of a force, producing chemical 
changes of the kind we are now considering, but acting only at one part, and 
in one direction. “ The capillaries which have taken on the appearance of inflam- 
mation, are all on one side of the fine membrane, and the serum and lymph, effu- 
sions from these vessels,” by which the diseased state is essentially characterized, 
“ are all on the other.”—(Goopsir, Anatomical and Pathological Observations, p. 43.) 
In saying that the fundamental property of chemical selection, essential to 
the growth of all living bodies, is strictly a vital property, we do not overlook the 
fact that various substances, composed of inanimate or inorganic matter, have 
likewise different powers of attraction for different elements or compounds 
- brought into contact with them. It appears to be only by reference to this pro- 
perty, that we can explain the well-known phenomena of endosmose and ex- 
osmose, in which different fluids, brought in contact with a solid body, are 
attracted into its pores with very different degrees of force. It is not the nature 
of the process by which the selection, in the case of the living body, is effected ; 
but the peculiarities of the selections themselves, their great force, and yet uniformly 
temporary existence, that entitle us to regard them as indicating a vital property. 
II. But when we attend to the peculiar changes effected by living solids on 
the fluid matters which are brought in contact with them, we find that these are 
by no means confined to the selection and appropriation, at particular points, of 

