ae ee ee PEE ee et ye PO he 4 
ee ote 
NN i NT 5S a ty 
as Infusoria flagellata. 213 
the general appearance of this part of the organism, it may be 
added that the older and basal portions (fig. 63) of the branches 
are flat, and have a distinct longitudinal irregular striation, 
to all Sona made up of the older, laterally agglutinated 
twigs. ‘The youngest, terminal portions (fig. 47, pd) of the 
branches which, under the name of twigs, have been described 
in this paper as the immediate supporters of the colonies of 
monads, are evidently tubular (fig. 62). They appear to be 
as flexible as a spider’s thread, and are usually quite irregular 
in outline, and in the calibre of the canal which permeates 
them. ‘The wall of these tubular twigs is quite thick, and is 
alike rough on the exterior and interior faces. The substance 
within the tubes appears homogeneous, but whether it is solid 
or fluid could not be determined. The oldest part of the 
_ stems is of a reddish-brown colour; but as they taper off into 
branchlets they gradually assume a gamboge-colour, and finally 
terminate in scarcely coloured twigs. 
“ Reproduction by fissigemmation (figs. 52-61) is the only 
method of propagating individuals which I have observed. 
As a preliminary to this process the monad gradually loses its 
fusiform shape, and assumes at first an oval contour, and finally 
becomes globular (fig. 52). During this transition, both of the 
prehensile cilia (7, #') become much more conspicuous than 
usual; and the body developes a closely fitting hyaline enve- 
lope (h) about it, thus passing into a sort of encysted state. 
The contractile vesicle (cv), however, does not seem to cease 
its pulsations during this period, and moreover it becomes 
quite conspicuous. ‘This arises mostly from the fact that the 
body is in a nearly quiet state, and allows the observer to ob- 
tain a | apa and undisturbed view of it. Unfortunately the 
rate of the pulsations of this organ was not ascertained when 
the following observations were made, because the whole time 
was occupied in watching and drawing the various and rapidly 
changing phases of self-division. 
. After the body assumes a globular shape, as above-men- 
tioned, both the larger and smaller cilium seem to be under- 
going a change, and become indistinct in outline. Presently 
two larger flagella (fig. 53, #1) burst upon the view, apparently 
by the longitudinal splitting of the previously aiaale one of 
the same kind, and rapidly separate from each other by the 
broadening of the body, leaving between them the smaller 
cilium. ‘The latter at this time appears much thicker than 
usual, and seems to be composed of two closely approximated 
parallel threads (ff!). By this time the contractile vesicle has 
also divided into two, which lie closely side by side. 
“‘ At this moment the time noted in one series of observa- 
