88 {HE VORTICELLID®. 
fame author is also responsible for the following account, which is thé 
most extraordinary of all. The process has never received any name, 
but it is that which I called acinetation on a former page, and the 
meaning of the term will be evident from the following description :—It 
commences, as in the last, by the encystation of the Vorticella, which in 
this case remains on the old stalk, or develops another. The bell then, 
by ® series of almost imperceptible changes, assumes the forms drawn at 
' Fig, 13, and from its two upper extremities sends out pseudopodia like 
those of an Actinophrys, and knobbed at the ends. This stage has long been 
known to microscopists under the name of Acineta, The nucleus, which 
is distinctly observable, divides into two, and one half becomes converted 
into an active Vorticella, acquiring an ovate form, a circle of cilia round 
one end, and a distinct mouth at the other, and inside it we may 
observe a nucleus and contractile vesicle. When mature it tears its way 
through the membraneous coat of the Acineta, and so becomes free, 
[Fig. 14.] The latter, however, immediately closes up, the nucleus 
divides again, and the process is repeated ud lib. 
When this extraordinary history was first given to the scientific 
world by Stein, it was contradicted, and at the present day is so much 
doubted that Huxley, in his recent work on Biology, when treating of the 
Vorticella, does not even mention it; but I think that Stein’s account is 
doubted chiefly because it lacks confirmation, andI therefore add just one 
grain of evidence in favour of its truth. One evening in October last, 
while examining some Acinetw from Barnt Green, I saw a small Vorti- 
cella burst from the body of one of them and swim away. 
Tn this last series of events we have an example of the phenomenon 
known as the alternation of generations. The Vorticella, instead of 
producing another being like itself, gives rise to an independent animal 
of totally different character, and this in the next generation, instead of 
giving birth to offspring of the same type, produces a Vorticella like the 
original. 
(2.) Carchesium polypinum, [Fig.3.] The name Carchesium is from 
the Greek karchesion, and signifies a goblet or drinking cup, which is 
narrower in the middle than at the top or bottom; polypinum, from 
polypus, a polyp, referring no doubt tothe appearance of the colony 
when expanded. It only differs from Vorticella in being branched, 
all the branches converging downwards to a single stem, [Figs. 3 and 4, ] 
which is spirally waved. Each branch contains a muscle, which 
is not connected directly with the one in the main stem, but is 
attached to the inside of the stalk; every bell, too, has a separate muscle. 
By this arrangement every branch is able to contract without the whole 
colony doing so, and even a single bell may contract without its fellows 
being affected. The colony originates from a single individual, by a 
continuous process of self-division, [Fig. 9;] the new animals, however, 
instead of breaking away, as in Vorticella, remain permanently on the 
old stem. I have observed gemmation in this species, but the two other 
methods of reproduction, viz., encystation and acinetation, I have not yet 
Witnessed, 
