580 SUPPLEMENT 
At other times they are observed to detach themselves spon- 
taneously, and swim, drawing after them their pedicle ex- 
tended in a right line. Finally, they sometimes fix them- 
selves by the enlarged part of their body, and appear to move 
by means of their appendages. This is chiefly observed in 
individuals whose pedicle is short, or even nothing, which is 
the case with the wrceolaria. 
It appears that there are vorticella attached one upon the 
other, so that they seem to constitute composite animals. 
The vorticelle, properly so called, multiply by natural 
sections, the body dividing by little and little in the middle, 
in such a manner, however, that the pedicle remains to a 
single individual. The promptitude with which this scission 
takes place is in proportion with the state of the external tem- 
perature, so that in fine weather, the multiplication of these 
animals goes on with wonderful rapidity. 
On the approach of winter, they produce oviform germs 
or buds, which are preserved in the water during the whole 
of this season, and are developed in spring. 
The vorticelle particularly live in fresh and stagnant 
waters, fixed upon all the bodies which are to be found 
there. 
Miiller has observed that the mode of generation in 
the species called V. racemosa, is altogether peculiar. An 
adult individual fixes itself upon some body. Then from its 
own body, or at the base, germinate eight similar bodies, 
which, in a few hours, are raised upon their own proper 
pedicles. In a short time, each of these new bodies gives 
birth to eight others, which provided in their turn with their 
pedicles, go on serzatim to propagate in the same manner. 
During this time the pedicles of the first and second order 
cross like the branches of a vegetable. As to the pedicle of 
the mother, and which supports all the others, it preserves 
the same length. 
