Note 9 — Chapter IV · Embryology.

I say “probably,” because analogy points in this direction. As a matter of fact, in many cases of tissue-formation karyokinesis has not hitherto been detected. But even if in such cases it does not occur—i. e. if failure to detect its occurrence be not due merely to still remaining imperfections of our histological methods,—the large number of cases in which it has been seen to occur in the formation of sundry tissues are of themselves sufficient to indicate some important difference between cells derived from ova (metazoal), and cells which have not been so derived (protozoal). Which is the point now under discussion.