256 Mr. J. J. Woodward on the Modern 
which protoplasm is composed, could by their combination, 
produce the characteristic phenomena of living protoplasm, 
namely, the phenomena of irritability, as I have just described 
them. But, in the second place, this speculation appears to 
be pretty flatly contradicted by the circumstance that, although 
protoplasm can only be formed within the substance of previ- 
ously existing living protoplasm, it can continue to exist, it 
does continue to exist as protoplasm after it has ceased to live. 
Not merely can it persist for a time without chemical change 
as dead protoplasm, it can subsequently serve as food and be 
reconverted into living protoplasm once more. Bear in mind, 
however, that this change can only be effected within the sub- 
stance of the living protoplasm of the animal that assimilates 
this food. It is not effected by the chemistry of digestion ; 
that merely makes peptone of the protoplasm—merely makes 
it soluble enough to pass into the substance of the protoplasmic 
masses that are to appropriate it. ‘These considerations, then, 
would seem to show that the material, protoplasm, cannot be 
rightly believed to be of itself the cause and essence of life. 
If I should pause here, it seems to me that I should have 
brought forward adequate reasons for believing in the existence 
of a vital principle. But I cannot pause here. Beyond and 
above all this there is another great group of phenomena 
peculiar to living beings—a group of phenomena concerning 
which, in my own individuality, | have knowledge at least as 
positive as any I possess of the existence of force, and which 
I am led, by a logic quite as convincing as that by which any 
general proposition with regard to the external world is proven, 
to believe exists in like kind and degree in the case of my 
fellow-man. I refer to the phenomena of the perceiving, 
emotional, will-full, reasoning human mind. Into the argu- 
ment that makes it highly probable that a similar but less 
and less perfect mind exists in the animal world, and iden- 
tifies with mind the sensibility of the lowest animal forms, 
and even that of vegetable protoplasm, I will not attempt to 
enter to-night. Mr. Herbert Spencer himself has presented 
this view with so much ingenuity, that, without committing 
myself to an approval of all his details, I must content my- 
self by referring you to his writings for one of the best discus- 
sions of this matter. It will be sufficient for my present 
purpose to close this discourse by the presentation of a few 
considerations in relation to mind as it exists in man. 
For myself I know mind only as a manifestation of life, if, 
indeed, it is not the essence of life. But the old doctrine of 
Epicurus, handed down to us in the poem of Lucretius, that 
in some way or fashion mind is produced by the clashing 
