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muscles and nerves. How is this riddle to be explained? Have 
we here a function without an organ, a soul without soul-apparatus? 
The decisive answer to this question is given us by the micro- 
scope. The cup-shaped body of the hydra consists really of two 
cups of equal size fastened into one another, whose walls closely 
touch each other on all sides. If we now observe thé thin fine 
section of double-wall of the hollow hydra body with a strong 
magnifying power, we see that the two cups consist each of a 
peculiar layer of cells. These two cell-layers have quite different 
properties and functions. The cells of the inner layer are exclu- 
sively concerned with the vegetative work of nourishment— 
digestion and assimilation. Those of the outer layer, on the 
contrary, negotiate the animal functions of sensation and motion. 
Now, if we pull to pieces this outer layer of skin with a needle, 
we shall observe in many of the separated skin-cells a long stringy 
process. More exact investigation shows that this thin stringy 
part of the cell runs circularly between the two layers round the. 
cup-shaped body, and causes the contraction of the latter, just like 
a muscle ; while the outer, roundish, nucleated part of the same 
cell has the power of sensation. We stand thus in face of the remark- 
able and highly important fact that a single cell, alone by itself, 
fulfils the most important duties of the soul: the outer, roundish 
part of the cell having sensation; the inner, thread-shaped part 
having will, voluntary motion. The outside half of the cell is 
nerve, the inner muscle; rightly therefore did Kleinenberg, the 
discoverer of these soul-cells of the hydra, call them “nerve- 
muscle-cells.” The whole soul-apparatus of our polyp consists in 
fact of nothing more than a simple layer of nerve-muscle cells, 
and each individual of these cells performs in simplest guise just 
what in vastly more elevated form the complicated soul-apparatus 
of the higher animals can do with its different nerve-muscles and 
_mind-cells. Naturally, however, here there is wanting entirely a 
central apparatus—a brain ; and instead thereof “the seat of the 
soul” is in our little polyp the wo/e outer skin. We need there- 
fore no longer wonder at the astonishing divisibility of the hydra, 
first made known in the year 1744 by Trembley’s experiments. 
