150 NEMATOPHYCE^). 



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 cir-cular 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 and a 

 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 CEdogonium has originated. From each spore there are thus 

 derived, in general, four plants. 



Plate LVI2. figs. 1-5. Stages in the formation of new cells after 

 Pringsheim. Fig. 6, male cells of Bulbochfste crassa, with spermogonia. 

 Fig. 7, zoospore of (Edogonium after Pringsheim. Figs. 8-10, develop- 

 ment of dwarf males after De Bary. Fig. 11, spermogonia. Figs. 

 12.13, imgregnation of CEdogonium ciliatum after Pringsheim. Fig. 14, 

 zoospore of CEdogonium rividare. Fig. 15, zoospore developing in its 

 mother-cell after Pringsheim. Fig. 16, zoospore of Bulbochcete 

 setigera. Figs. 17-19, segmentation of resting spores of (Edogonium. 

 Fig. 20, oospore escaping from oogonium. Fig. 21, mature oospore of 

 JBulbochtete undergoing division. Fig. 22, four zoospores developed 

 .from the same. Fig. 23, sterile cells of (Edogonium Reinschii. All 

 magnified 400 diam. 



The following is an arrangement of British species, on the basis of 

 Wittrock's " Monograph " : 



CEDOGONIUM. 

 Sect. 1. Species monoecious. 



A. Oogonia always destitute of median processes. 



a. Oospores globose or subglobose. 



a Oogonia globose or subglobose. 

 CE. Petri, Wittr. 

 CE. cryptosporum, Wittr. 

 CE. curvum, Pringsh. 

 CE. cymatosporum, W. % N. 

 CE. minus, Wittr. 

 CE. vernale, Hass. 

 CE. crispum, Hass. 

 CE. Vaucherii, Le Cl. 



/3 Oogonia elliptic or egg-shaped, 

 CE. urbicum, Wittr. 



b, Oospores ellipsoid or egg-shaped, 



CE. palndosum, Hass. 



