THE VORTICELLIDE. 87 
then flattened at the top. Presently a constriction appears, extending 
from the top downwards, [Fig. 8,] and this deepens till the bell is cut 
into two halves, only connected by the stem, which is common to both, 
The one which is to remain on the old stem now re-opens its ciliary 
wreath, but on the other, which will ultimately break away, a new wreath is 
formed at the end nearest’ the point of attachment, [Fig. 9.] The new 
cilia appear first as loose hairs, moving listlessly to and fro in the water, 
but these soon lengthen, their strokes increase in vigour and rapidity till 
the bell trembles as if impatient to be off. It now begins to revolve, 
slowly at first, then gradually faster and faster, till the slender point of 
connection snaps, and away shoots the bell, gliding swiftly and merrily 
through the water. After whirling about for some time, it chooses a 
place of rest, settles down, and after brooding over it for some time, 
begins to rise by the growth of a new stalk, which soon attains a 
considerable length. The cilia have by this time disappeared, and a 
third set is formed at the top, so that now the animal resembles in 
every respect the parent from which it sprang. 
Gemmation, or budding, is not of nearly so frequent occurrence. I 
have not seen it myself in Vorticella, though it does occur, but I have 
seen it in Carchesiwm polypinum, [Fig. 15.] The process is very 
similar to the last, but the new animal, instead of being formed from 
one-half of the old one, is produced near its base by the expansion of 
the cuticle into a kind of protuberance or bud, which is nourished, as 
in Hydra, by the parent, the body cavities of both being continuous 
with one another. As in the last case, the bud develops a circle of 
cilia near its attached end, and breaks away to find a home elsewhere. 
The two remaining reproductive processes are inseparably connected 
with the organ called the “nucleus.” This organis present in all the 
Infusoria, and is almost universally believed by zoologists to be of a 
sexual nature, but what are its precise attributes remains at present a 
mystery. But whatever may be its function, the part it plays in the 
two following events is very remarkable. In all the Vorticellide it is 
long and band-like, and in the species now under consideration it is 
curved like the letter C. 
The Vorticella at an-earlier or later period of its existence with- 
draws the disc and circle of cilia, and contracting itself into a ball 
secretes a gelatinous covering or cyst, which gradually solidifies. The 
body of the animal [Fig. 10] now appears almost homogeneous, but still 
contains the nucleus unchanged, and the contractile vesicle, which has 
now lost all power of contraction, and remains permanently expanded: 
The nucleus next breaks up into a number of oval discs, [Fig. 11,] which 
move about in the thin, gelatinous mass into which the substance of the 
parent has become dissolved. The cyst now becomes filled with separate 
little sacs, which finally break through its walls and eject their gela- 
tinous contents with the included embryos into the water, there to give 
rise to anew generation of Vorticelle. I regret that I have never been 
able to see this mode of propagation, and the only author who really 
appears to have observed it is Stein, on whose authority I give it. The 
