150 NEMATOPHYCES. 
behind the outer membrane, enclosing the inner one. After the four 
cells have remained some time enclosed in the hyaline covering, this 
becomes resorbed subsequently, and the four cells lie still and motion- 
less, but after the course of a short time the cells burst on one end by 
means of an annular slit, and the apex, separated thereby from the 
remainder of the cell-membrane, becomes elevated like a lid. Through 
the circular opening the cell contents now emerge, which at the part 
turned towards the opening is colourless. This apex moves with 
vigorous motion backwards and forwards, and after an hour*the cell 
contents, in the form of a zoospore, leave their place of detention, which 
we now find to be a doubly-coloured cell-membrane. The little zoospore 
wheels in a lively manner about with a circling movement, whereby the 
colourless point becomes directed downwards. Its appearance is like 
that of an ordinary zoospore, and, like it, possesses an oval form anda 
lighter apex, furnished with cilia, which during the motion is always 
directed forwards. After a time the movements become faint, and 
finally cease. The cilia disappear, and the light end becomes elongated 
into a root, which sometimes becomes an organ of attachment, quite 
like that produced in the germination of the ordinary zoospores. The 
rounded end of the germinating zoospore acquires a little point-like 
apex. This growth becomes divided by a transverse septum, and a little 
two-celled (dogonium has originated. From each spore there are thus 
derived, in general, four plants. 
Plate LVII. figs. 1-5. Stages in the formation of new cells—after 
Pringsheim. Fig. 6, male cells of Bulbochete crassa, with spermogonia. 
Fig. 7, zoospore of @dogonium—after Pringsheim. Figs. 8-10, develop- 
ment of dwarf males—after De Bary. Fig. 11, spermogonia. Figs. 
12.13, imgregnation of @dogonium ciliatum—after Pringsheim. Fig. 14, 
zoospore of Cdogonium rivulare. Fig. 15, zoospore developing in its 
mother-cell—after Pringsheim. Fig. 16, zoospore of Bulbochete 
setigera. Figs. 17-19, segmentation of resting spores of Gdogonium. 
Fig. 20, oospore escaping from oogonium. Fig. 21, mature oospore of 
Bulbochete undergoing division. Fig. 22, four zoospores developed 
from the same. Fig. 23, sterile cells of Gdogonium Reinschii. All 
magnified 400 diam. 
The following is an arrangement of British species, on the basis of 
Wittrock’s “ Monograph ” :— 
CDOGONIUM. 
Sect. 1. Species moncecious. 
A. Oogonia always destitute of median processes. 
a. Oospores globose or subglobose. 
a Oogonia globose or subglobose. 
Gi. Petri, Wittr. 
:. cryptosporum, Wittr. 
Ck. curvam, Pringsh. 
G. cymatosporum, W, § NV. 
G. minus, Wittr. 
&. vernale, Hass, 
CG. crispum, Hass. 
G. Vaucherii, Le Cl. 
B Oogonia elliptic or egg-shaped, 
G. urbicum, Wittr. 
b, Oospores ellipsoid or egg-shaped. 
CG. paludosum, Hass. 
