VOLVOCINEE, 51 
Chlamydococcus pluvialis. Br. Rejuvenescence, p. 206. 
Cells subglobose, very variable in size, brownish red, chang- 
ing in some conditions to green. 
Size. Cells 007-085 mm. 
Rabh. Alg. Enr, viii, 98. Cohn Nova Acta. xxii. p. 749, 
t. 67 A. B. Pritchard Infus. 523, t. xix. f. 20-31. TT. OC. 
White, in “ Quekett Microscopical Journ.,” vi. p. 43. 
Hematococcus pluvialis. Flotow, Nova Acta xx. 
Hematococcus Corda. Meneg. Nost. p. 20, t. 1, f. 5. 
Hematococcus mucosus. Morren Rubefact : des Eaux, t. 6, 
f, 10-20. 
Protococcus pluvialis, Kutz. Tab. i. f. 1. Cohn, Memoir 
on Protococcus. 
Protococcus monospermus. Corda, in Sturm Flora ii. 25. 
On rocks, stones, &c., in hollows filled with rain water. 
“Normally fully developed cells of this multiform creature, sometimes 
like a plant, sometimes like an animal, present the appearance of glo- 
bules from ‘02 to ‘04 mm. diam., with a thick, tough cell membrane, and 
granular-punctate, opaque contents, sometimes of a brown, sometimes (at 
other periods, or in other localities) bright red colour. In the mass of 
the dark contents lie hidden several other structures, which at this period 
are completely concealed, namely 4-6 starch globules of °0033 or at 
most ‘005 mm. in diameter, in which, asin those of Hydrodictyon, a 
nucleus and an envelope may be distinguished, acquiring a violet colour 
with iodine, the nucleus becoming rather redder. Sulphuric acid causes 
a considerable swelling up of the coat. There also appears to exist in 
the centre of the cell a large, very delicate nuclear vesicle, which, how- 
ever, is so covered up by the rest of the cell contents, that it can only 
be very indistinctly perceived, and cannot even be clearly displayed 
when the contents are squeezed out. When these resting globular cells 
are placed in water they give birth to four gonidium-like swarming 
cells. Even before the commencement of the division of the contents 
by which the latter are formed, a change begins in the colour of the 
parent cell, the red colour retreating to some extent from the periphery, 
and a yellow (sometimes rather greenish) border forming round the deep 
redinner mass. The young swarmers also, for a short time after they 
issue out, have only a narrow yellow rim round a dark red middle. 
During the two or three days’ period of movement and growth of these 
swarming cells—in which they grow to about four times the original 
size, changing their obtusely ovate form at the same time toa reversed 
. pear-shaped apiculated shape—important new changes take place in the 
contents of the cells. The red colour becomes more and more concen- 
trated into the middle of the cell, so that a sharply defined bright 'red 
nucleus is formed, in the interior of which a lighter space is often 
clearly perceptible, corresponding to the nuclear vesicle above-men- 
tioned, around which the red colouring matter forms a covering, mostly 
complete, but sometimes imperfect and interrapted. The rest of the 
cell contents have become a brilliant green, and in them may be clearly 
distinguished the above-mentioned starch granules, as well as many 
more smaller green granules. The ciliated point of the cell, often 
drawn out like a beak, is colourless. This first moving generation is 
succeeded by a not yet accurately determined number of similar active 
generations populating the water for some weeks, and often giving it a 
bright green colour, till at length universal rest recommences, and the 
