205 
The Struggle for Life within the 
Animal Body. 
By Puitie B. Mason, M.R.C.S., F.L.S. 
Read before the Society, December 12th, 1895. 
al le the Address to which you did me the honour to 
listen at the commencement of our last Session, I 
attempted to prove, that men and animals, not only indi- 
vidually, but also in communities, are engaged in a ceaseless 
struggle for life; and further, that the condition of the 
world at any given moment, represents the momentary 
equilibrium produced by the sum of these struggles. From 
this I made the deduction, in truth a matter of the easiest 
observation, that this condition must and does vary from 
moment to moment. 
To-night I am again asking your indulgence while I 
endeavour to show that what is true of the macrocosm of 
the world, is also true of the microcosm of the animal body. 
For this purpose I will as shortly, and in words as plain 
as possible, sketch the fundamental plan on which the 
animal body is constructed, how it increases in complexity 
as the scale of animal life is ascended, how it grows, how 
it is nourished, and finally, how it is protected from its 
enemies, both domestic and foreign. I do this the more 
willingly, because the researches of the last few years have 
not only opened up new vistas of knowledge, but also 
completely revolutionised opinions, held universally but a 
short time ago. 
