62 THE MICROSCOPICAL NEWS. 
This operation, which probably many of you have witnessed, begins 
by a slight constriction appearing about the middle of the body, 
and this goes on gradually increasing until the two ends are almost 
separated, when it is most interesting and amusing to see the 
tugging which takes place between the two halves with a view to 
entire separation; we see also threads of protoplasm drawn out 
between the adjoining ends, and, when at last the final tug is given, 
these threads break and leave each of the two new paramecia duly 
provided with cilia, and so fitted to begin life anew, on a reduced 
scale. Now in the case of these ciliated infusoria there is a 
total absence of nerves, muscles, or other visible organisation 
which accounts for the movement, and yet we have, these cilia 
vibrating rapidly to and fro producing definite currents in the water, 
the principal one being in the direction of the mouth, and thus 
bringing the necessary supply of food. It is evident that to pro- 
duce such a current it is not enough that the cilia should move, 
but that they should move in a definite manner, and in harmony 
with one another. And similarly with the Flagellate infusoria, 
monads and similar organisms which swim gracefully through the 
water by means of flagella, the motion, to be of use either as a 
means of locomotion or of procuring food, must be of a definite kind 
—and we find that where flagellates form colonies, as in the Volvox 
globator, and others, the flagella of the individuals vibrate in har- 
mony with each other as is evidenced by the regularity of the current 
produced, united action being essential to such regularity. It has 
been suggested that this vibratory movement of cilia is caused by the 
alternate contraction and expansion of their opposite sides—one 
side expanding while the other contracts, and wce versa; and this 
is, perhaps, not an unreasonable explanation, but it is not a com- 
plete one; the question still remaining as to the cause of the 
contractions and expansions. The same explanation might apply 
to flagella, but the objection would apply still more strongly, 
their movements not being so simple apparently, as those of cilia. 
They frequently move in a sort of spiral or corkscrew fashion, and, 
moreover, are often used for prehensile purposes, much the 
same as the trunk of an elephant. With one of these flagellated 
infusoria—a fixed one inhabiting a beautiful tiny transparent vase— 
which I saw some time since, I was very much struck ; its mode 
of projecting and retracting its flagellum differing from anything I 
had seen elsewhere, and its singularity will perhaps be considered 
a sufficient excuse for my referring to it. When retracted, the 
flagellum was coiled up into a regular circular volute, which, on 
being projected, uncoiled much in the same way as a straight 
ribbon of well tempered spring steel similarly coiled would have 
done, but much more slowly and gracefully. This, on the theory 
I have alluded to, would indicate a very curiously modified power 
