CHAPTER XII 
PROTOPLASM, THE PHYSICAL BASIS OF LIFE 
THE recognition of the réle that protoplasm plays in the 
living world was so far-reaching in its results that we take 
up for separate consideration the history of its discovery. Al- 
though it is not yet fifty years since Max Schultze established 
the protoplasm doctrine, it has already had the greatest 
influence upon the progress of biology. Too the consideration 
of protoplasm in the previous chapter should be added an 
account of the conditions of its discovery, and of the person- 
ality and views of the men whose privilege it was to bring 
the protoplasm idea to its logical conclusion. Before doing 
so, however, we shall look at the nature of protoplasm 
itself. 
Protoplasm.—This substance, which is the seat of all 
vital activity, was designated by Huxley ‘“‘ the physical basis 
of life,” a graphic expression which brings before the mind the 
central fact that life is manifested in a material substratum 
by which it is conditioned. All that biologists have been able 
to discover regarding life has been derived from the observa- 
tion of that material substratum. It is not difficult, with the 
help of a microscope, to get a view of protoplasmic activity, 
and that which was so laboriously made known about 1860 
is now shown annually to students beginning biology. 
Inasmuch as all living organisms contain protoplasm, 
one has a wide range of choice in selecting the plant or the 
animal upon which to make observations. 
We may, for illustration, take one of the simplest of animal 
organisms, the amoeba, and place it under the high powers 
259 
