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

A ORTTIOISM OP THE OELL-THEORY. 171
cells, recent researches on cell lineages may perhaps give us
a clue to the interpretation of the fact that blastomeres are
in so many cases, no more than coherent. For it is noticeable
that wherever cell lineages, with marked isolation of the blastomeres,
have been described, there is a decided tendency to the
precocious development of organs, or, at any rate, to the precocious
isolation of the primordia (Anlage) of organs.
It seems probable that the discrete condition of the blastomeres
is connected with the fact, to which I alluded in the
earlier part of this essay, that they are, from the very outset,
specialised. They have each a definite molecular constitution
different from the others, and, in figurative language, a
limited part to perform, which they could not perform to
advantage if they were conjunct with the other blastomeres
and shared in their different molecular constitution. But
this is a subject which I must leave for a future occasion when
I discuss the validity of von Baer's law of development.
( I have travelled in this essay over a great deal of ground,
and I have necessarily had to touch more lightly on many
topics than I should have wished. I hope that I may at
least have succeeded in presenting my arguments in a manner
which will make them clear to my readers, and that I have not
been too discursive. Starting from Mr. Sedgwick's propositions
and accusations, I have tried to show what is or was the exact
extent and meaning of the cell-theory ; I have tried to examine
it and show how much was good and how much bad, and I
have finally been led to the conclusion—which is not quite
what I proposed to myself at the outset—that the cell concept
is a valuable expression of our experience of organic life, both
morphologically and physiologically, but that in higher organisms
cells are much what von Sachs declares them to
be, not independent life units (Lebenseinzelheiten), but a
phenomenon so general as to be of the highest significance;
they are the constant and definite expression of the formative
forces which reside in so high a degree in organic matter.
Lest I should appear to have minimised the importance of
the cell too much, let me conclude by saying, that nothing