2 LIVERPOOL BIOLOGICAL SOCIETY. 
attached to matter, on a certain susceptibility of being 
excited, residing in other matter. ‘‘In all states of life,”’ 
says John Brown, ‘‘man and other animals differ from 
themselves in their dead state, or from any other 
inanimate matter, in this faculty alone that they can be 
affected by external agents, as well as by certain func- 
tions peculiar to themselves, in such a manner that the 
phenomena peculiar to the living state can be produced.” 
The great merit of this view is the introduction of a second 
factor, viz., the co-operation of an external agency, or 
what is now called the environment, as essential to the 
very process in which life is stated to consist. The idea of 
Spontaneity or Spontaneous activity inseparable from the 
notion of an independent Vital Principle is likewise shut 
out, and biology is brought within the circle of the true 
sciences. 
The view of life as a process dependent on two factors 
spread rapidly among physiologists during the generation 
following John Brown’s day, being adopted by Blumenbach, 
Reil, Cuvier, Bichat, Richerand, Roland, Lawrence and 
others. Since then it, or at least the idea of life as a process 
rather than a substantive principle may be said to be almost 
universally held, and is the foundation of the variously 
expressed definitions of life as the sum of the actions or 
functions which will be considered presently. In the 
meantime, however, we may notice that the word Vitality 
cannot be used as synonymous with life, for it is only one 
factor in the actions which constitute life. It is merely a 
property of a certain collocation of matter we know as 
‘organised,’ which when acted on by appropriate powers 
in the environment, is competent to give rise to the 
actions in which life consists. If, however, vitality is 
merely a property, resulting from their peculiar chemical 
composition, of the separate anatomical elementary units 
