greatly astonished to find the blood-cells themselves more or less
filled with the particles of indigo after a few hours. After repeated
injections I succeeded in "observing the very entrance of the coloured
particles in the blood-cells, which took place just in the same way as
with the amoeba." I have given further particulars about this in my
Monograph on the Radiolaria.)

We now see very clearly how extremely important the cell theory has
been for our whole conception of organic nature. "Man's place in
nature" is settled beyond question by it. Apart from the cell theory,
man is an insoluble enigma to us. Hence philosophers, and especially
physiologists, should be thoroughly conversant with it. The soul of
man can only be really understood in the light of the cell-soul, and
we have the simplest form of this in the amoeba. Only those who are
acquainted with the simple psychic functions of the unicellular
organisms and their gradual evolution in the series of lower animals
can understand how the elaborate mind of the higher vertebrates, and
especially of man, was gradually evolved from them. The academic
psychologists who lack this zoological equipment are unable to do so.

This naturalistic and realistic conception is a stumbling-block to our
modern idealistic metaphysicians and their theological colleagues.
Fenced about with their transcendental and dualistic prejudices, they
attack not only the monistic system we establish on our scientific
knowledge, but even the plainest facts which go to form its
foundation. An instructive instance of this was seen a few years ago,
in the academic discourse delivered by a distinguished theologian,
Willibald Beyschlag, at Halle, January 12th, 1900, on the occasion of
the centenary festival. The theologian protested violently against the
"materialistic dustmen of the scientific world who offer our people