ORGANIC AND INORGANIC KINGDOMS. 
181 
manifestation. It is involved in every vital act. And the power of com¬ 
pensating for this waste or change, the repair or reproduction necessary to 
the continuance of life, involves that of assimilation—the power of convert¬ 
ing foreign matters into the structure of the organism: in other language, 
the power of appropriating food. 
We cannot conceive life without including these two conditions— 
consumption and supply. Life is not a state of change only as opposed to 
stability; for this is simply a question of degree everywhere, and dependent 
on the conditions to which bodies are exposed. Neither dead organic nor 
inorganic bodies are immune from change. Nor is life peculiar as a process 
of repair only; for this may occur in inorganic bodies, as crystals, under 
favourable circumstances. But in life there is the constant and concurrent 
operation of these two processes, whereby it is distinguished from mere 
change on the one hand, and from repair on the other. 
It does not appear that we can at present safely venture further than 
this. If we attempt to define the vital process of nutrition, distinctions 
fail us. 
The investigation of the phenomena of life has not been in any way 
assisted, our knowledge of the vital processes has not been in any measure 
advanced, by the assumption of what has been styled a “ vital principle 
—an empirical term, which, like some others when employed in physiology, 
is, even at the best, equivalent to nothing more than the final letters of the 
alphabet in an algebraical formula; for it is, when used in its least objectionable 
sense, a mere expression of something unknown. But the assumption of 
such an agent or principle, however designated, annihilating or suspending 
the operation of forces acting elsewhere, has not proved altogether harmless 
in its influence upon the progress of knowledge. By referring all vital 
actions to this obscure agency, while nothing was thereby explained, inquiry 
was to a great extent, and for a long while, checked. Many dazzled by 
the idea that the nature of vital phenomena was exalted by thus associating 
them with some mysterious and peculiar principle apart from, and opposed 
to those agencies which act elsewhere, missed the grander conception, that 
even in the vital functions may be recognised the operation of forces, some 
of which, at least, are common to both kingdoms of nature; while, between 
these and others which appear to be peculiar to living tissues, it is probable 
that a relation may exist like that which prevails between the chemical and 
physical forces. 
Again, it is needful to beware how we create artificial distinctions. Is 
there not much assumption involved in the confession that we are unable to 
construct the simplest form of living tissue? Men sometimes talk as if 
their powers were limited only by life. But can we construct a crystal any 
more than a nucleated cell? We may fulfil certain conditions, under 
which, as we have learned from experience, crystals are formed ; but what 
is our share in the act itself? In like manner we may take a seed or an egg, 
and place them under circumstances in which they will develope. In either 
case we are acquainted with the necessary conditions, and we fulfil them. 
We can do no more. 
The speaker concluded with some remarks on the fact that the tendency 
of advancing knowledge is to efface the lines of demarcation which have 
been hitherto drawn between the Natural Kingdoms. 
