VOLVOCINES. 65 
Gznus 40, EUDORINA. E£hrbd. (1831.) 
Ccenobium oval, involved in a common tegument ; cells green, 
globose (16-32), enclosed within a single membrane, bearing 
vibratile cilia, often with a red spot (eye-spot), distributed 
around the hyaline sphere at equal distances apart. Asexual 
propagation in all the ccenobia, the cells of which are divided 
into 16-32 parts, and soon evolved into new ceenobia. Sexual 
propagation in all the ccenobia, the cells being converted into 
motionless oospores enclosed in a narrow epispore, afterwards 
becoming red. 
The most complete account we possess of the life-history of Eudorina 
is that by H. J. Carter (Ann. Nat. Hist., Oct., 1858), of which the follow- 
ing is asummary:—Unable to recognise this organism in its simplest 
form as a solitary cell, nor any stage of segmentation prior to the third 
degree of duplicative subdivision into 16 cells, he commences from this 
period. 
At this time, which we call the first stage, the Hudorina consists of an 
ovoid green body, partially divided into the number of cells just men- 
tioned, each of which is provided with a pair of cilia, which project 
through a thin gelatinous envelope that surrounds the whole mass. ‘It 
is now about 1-1100ths of an inch long, ¢.e., not more than the diameter 
of the Chlamydococcus cell, and swims by means of its cilia, with the 
small end foremost, and with a rotatory motion on its longitudinal axis, 
as often from right to left as from left to right. An eye-spot is also 
present in each of the four anterior cells, but seldom visible in the rest 
at this period. 
As development progresses each cell is provided with a spherical, 
translucent utricle, an eye-spot midway between the cilia and the oppo- 
site end of the cell, a contractile vesicle at the base of the cilia, and the 
pair of cilia themselves. 
During the second stage each of the cells again undergoes duplicative 
division, and the whole organism becoming larger, they are separated 
from each other, and being no longer subject to compression, become 
spherical and enclosed respéctively within distinct transparent capsules. 
The Zudorina is now six times as long as in the first stage, and contains 
32 green cells, which are evidently situated between two large ovoid, 
colouriess, transparent cells, one of which bounds a similarly shaped 
cavity in the centre of the Hudorina, and the other is the original cell 
wall, round which again is the newly secreted envelope. Thus we see 
that the Zudorina is derived from a simple (daughter) cell, and that its 
green cells have resulted from a duplicative subdivision of the green 
matter which lined the cavity of this cell. Arrived at this state, which 
we shall see is that of maturity, we also observe that the posterior part 
of the envelope becomes crenulated, apparently from flaccidity. 
After this, however, it again presents another phase, which may be 
called the third, or last, stage of development. Here each cell again 
undergoes a rapid duplicative subdivision into 16 or 82 cells, which, in 
the group, assume a more or less oblong figure respectively, and thus the 
Eudorina’s length is increased to 10 times that of its first stage. The in- 
ternal structure now gradually breaks down before the external envelope, 
when for a short time the groups may be seen swimming about the cavity 
thus formed, till at last the envelope bursts and they become liberated. 
What becomes of them afterwards he could not state from observation, 
but the green cells having been greatly reduced in size by the latter sub- 
