I
With his usual vigor and expressiveness Henry Drummond has given us a
picture of the remarkable fact that the cells of all plants and animals
are strikingly alike, especially the single cells from which all
originate. It is easy for any one to distinguish between an oak, a palm
tree, and a lichen, while a botanist will have elaborate scientific
distinctions which he can discern between them. "But if the first young
germs of these three plants are placed before him," says Drummond, and
the botanist is called upon to define the difference, "he finds it
impossible. He cannot even say which is which. Examined under the
highest powers of the microscope, they yield no clue. Analyzed by the
chemist, with all the appliances of his laboratory, they keep their
secret.
"The same experiment can be tried with the embryos of animals. Take the
ovule of the worm, the eagle, the elephant, and of man himself. Let the
most skilled observer apply the most searching tests to distinguish the
one from the other, and he will fail.
"But there is something more surprising still. Compare next the two
sets of germs, the vegetable and the animal, and there is no shade of
difference. Oak and palm, worm and man, all start in life together. No
matter into what strangely different forms they may afterwards develop,
no matter whether they are to live on sea or land, creep or fly, swim or
walk, think or vegetate,--in the embryo, as it first meets the eye of
science, they are indistinguishable. The apple which fell in Newton's
garden, Newton's dog Diamond, and Newton himself, began life at the same
point."[10]
In these remarks, of course, Drummond is dealing with the unicellular
primal form, "as it first meets the eye of science"; and while certain
slight peculiarities (such as the constant number of chromosomes) have
been detected as characteristic of the cells of certain forms, yet for
all practical purposes these words of Drummond are just as true to-day
as when first written. Possibly it is because of a failure in our
technique or from a lack of power in our microscopes that these
wonderful protoplasmic units from which all living things originate seem
identical. But it is equally possible that they _are really identical_
in structure and in chemical composition, and that only the ever present
watchcare of the great Author of nature directs the one to develop in a
certain manner, "after its kind," and another in still another manner,
"after its kind." At any rate, the _protoplasm_ of which they are all
alike composed _is_ identical wherever found, so far as any scientific
tests have yet been able to determine.
[Footnote 10: "Natural Law," Chapter X.]