d from germ-cells--no matter how many generations of
budded organisms may have intervened. And that propagation by budding,
&c, in multicellular organisms is thus ultimately due to their
propagation by sexual methods, seems to be further shown by certain
facts which will have to be discussed at some length in my next volume.
Here, therefore, I will mention only one of them--and this because it
furnishes what appears to be another important distinction between the
Protozoa and the Metazoa.

In nearly all cases where a Protozooen multiplies itself by fission, the
process begins by a simple division of the nucleus. But when a Metazooen
is developed from a germ-cell, although the process likewise begins by a
division of the nucleus, this division is not a simple or direct one; on
the contrary, it is inaugurated by a series of processes going on within
the nucleus, which are so enormously complex, and withal so beautifully
ordered, that to my mind they constitute the most wonderful--if not also
the most suggestive--which have ever been revealed by microscopical
research. It is needless to say that I refer to the phenomena of
karyokinesis. A few pages further on they will be described more fully.
For our present purposes it is sufficient to give merely a pictorial
illustration of their successive phases; for a glance at such a
representation serves to reveal the only point to which attention has
now to be drawn--namely, the immense complexity of the processes in
question, and therefore the contrast which they furnish to the simple
(or "direct") division of the nucleus preparatory to cell-division in
the unicellular organisms. Here, then (Fig. 29), we see the complex
processes of karyokinesis in the first two stages of egg-cell division.
But similar processes continue to repeat themselves in subsequent
stages; and this, there is now good reason to believe, throughout _all_
the stages of cell-division, whereby the original egg-cell eventually
constructs an entire organism. In other words, all the cells composing
all the tissues of a multicellular organism, at all stages of its
development, are probably originated by these complex processes, which
differ so much from the simple process of direct division in the
unicellular organisms[9]. In this important respect, therefore, it does
at first sight appear that we have a distinction between the Protozoa
and the Metazoa of so pronounced a character, as fairly to raise the
question w