PRESIDENTS ADDRESS. 7 
nation.* It is therefore certain that such movements are not specifically 
‘ vital,’ that their presence does not necessarily denote ‘life.’ And 
when we investigate closely even such active movements as those of a 
vibratile cilium or a phenomenon so closely identified with life as the 
contraction of a muscle, we find that these present so many analogies 
with amceboid movements as to render it certain that they are funda- 
mentally of the same character and produced in much the same 
manner. Nor can we for a moment doubt that the complex actions 
which are characteristic of the more highly differentiated organisms 
have been developed in the course of evolution from the simple move- 
ments characterising the activity of undifferentiated protoplasm ; move- 
ments which can themselves, as we have seen, be perfectly imitated 
by non-living material. The chain of evidence regarding this particular 
manifestation of life—movement—is complete. Whether exhibited as 
the amceboid movement of the proteus animalcule or of the white 
corpuscle of our blood; as the ciliary motion of the infusorian or of 
the ciliated cell; as the contraction of a muscle under the governance 
of the will, or as the throbbing of the human heart responsive to every 
emotion of the mind, we cannot but conelude that it is alike subject 
to and produced in conformity with the general laws of matter, by 
agencies resembling those which cause movements in _ lifeless 
material.® 
It will perhaps be contended that the resemblances between the 
movements of living and non-living matter may be only superficial, 
and that the conclusion regarding their identity to which we are led 
will be dissipated when we endeavour to penetrate more deeply into the 
working of living substance. For can we not recognise along with the 
possession of movement the presence of other phenomena which are 
equally characteristic of life and with which non-living 
eee material is not endowed? Prominent among the charac- 
similation. teristic phenomena of life are the processes of assimilation 
and disassimilation, the taking in of food and its elabora- 
> The causation not only of movements but of various other manifestations 
of life by alterations in surface tension of living substance is ably dealt with 
by A. B. Macallum in a recent article in Asher and Spiro’s Hrgebnisse der 
Physiologie, 1911. Macallum has described an accumulation of potassium salts 
at the more active surfaces of the protoplasm of many cells, and correlates this 
with the production of cell-activity by the effect of such accumulation upon the 
surface tension. The literature of the subject will be found in this article. 
4G. F. FitzGerald (Brit. Assoc, Reports, 1898, and Scient. Trans. Roy. 
Dublin Society, 1898) arrived at this conclusion with regard to muscle from 
purely physical considerations. 
5 ‘Vital spontaneity, so readily accepted by persons ignorant of biology, 
is disproved by the whole history of science. Every vital manifestation is a 
response to a stimulus, a provoked phenomenon. It is unnecessary to say this 
is also the case with brute bodies, since that is precisely the foundation of the 
great principle of the inertia of matter. It is plain that it is also as applicable 
to living as to inanimate matter.’—Dastre, op. cit., p. 280. 
