A Criticism of the Cell-Theory; being an Answer to Mr. Sedgwick's ...

A CRITICISM OP THE DELL-THEORY. 139
It is probably a fair summary of his position to say that, for
the present, he limits his objections to the application of the
cell-theory to the process of growth during embryonic development
j but that he scarcely conceals his preference for the
view that there are no such things as discrete cells in the
so-called multicellular organism. And as it is necessary, at
the outset, to have a perfectly clear idea of his meaning, I will
quote passages from the work to which he refers in his opening
paragraph, assuming that what he stated then he is prepared
to adhere to now, and that his last article is intended to
emphasise the views which he formerly propounded, and to
bring fresh evidence in support of them.
On p. 204 of the second part of his account of the development
of the Cape species of Peripatus, he says:—"It is
becoming more and more clear every day that the cells composing
animal tissues are not isolated units, but that they are
connected with one another. I need only refer to the connection
known to exist between connective tissue cells, cartilage
cells, epithelial cells, &c. And not only may the cells of one
tissue be continuous with one another, but they may also be
continuous with the cells of other tissues. ... It is true
that the cells of blood and lymph and the ripe generative cells
are completely isolated. But the former, in their first stages
of growth, form part of the syncytium, as in all probability do
the latter also. This continuity, which for a priori reasons
we should expect, has hitherto been regarded as a fact of little
morphological importance and relegated to the category of
secondary features. The ovum, it is said, segments into
completely isolated cells, and the connection between them is
a secondary feature acquired late in development. It has
always been considered that the first stage in the evolution
of the Metazoa was a colonial Protozoon, i. e. a mass of perfectly
isolated unicellular organisms, derived by complete division
from a single cell. Now while I do not wish to exalt the facts
of the cleavage and early development of Peripatus to a position
of undue importance, or to maintain that of themselves
they are sufficient to destroy this conception of the origin and