What can this wonder glass do in the way of drawing boundary lines
betwixt the living worlds? The reply again is disappointing to the
doubter; for the microscope teaches us that the tissues of animals and
plants are built upon kindred lines. We meet with cells and fibers in
both. The cell is in each case the primitive expression of the whole
organism. Beyond cells and fibers we see the wonderful living
substance, _protoplasm_, which is alike to our senses in the two
kingdoms, although, indeed, differing much here and there in the
results of its work. On purely microscopic grounds, we cannot separate
animals from plants. There is no justification for rigidly assuming
that this is a plant or that an animal on account of anything the
microscope can disclose. A still more important point in connection
with this protoplasm question consists in the fact that as we go
backward to the beginnings of life, both in animals and plants, we
seem to approach nearer and nearer to an identity of substance which
baffles the microscope with all its powers of discernment. Every
animal and every plant begins existence as a mere speck of this living
jelly. The germ of each is a protoplasm particle, which, whatever
traces of structure it may exhibit, is practically unrecognizable as
being definitely animal or plant in respect of its nature.
Pages:
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194