802 SUMMAKY OF CUERENT RESEARCHES RELATING TO 



has nevertheless determiBed that they are the result of repeated 

 bipartition of the protoplasm, the whole process taking four or five 

 days. Before escaping, the biciliated zoospores are always sur- 

 rounded by a gelatinous mass, the whole mass rupturing both the 

 cell-wall of the CMorochytrium and the tissue of the Lemna before the 

 zoospores are endowed with motion. While still enclosed in the 

 jelly, the zoospores are seen to imite in pairs by their apices into an 

 hourglass-shaped body, in which condition they whirl rapidly round 

 one another, and then coalesce into a nearly spherical zygozoospore. 

 These finally with their apices bore through the gelatinous envelope, 

 and move about freely by means of their four cilia. Some, however, 

 never succeed in breaking through the envelope ; this at length dis- 

 appears, as do those which, after moving about, do not come in con- 

 tact with Lemna. Klebs was not able to detect the tubular processes 

 described by Cohn, by means of which the zoospores escape, nor the 

 two kinds of zoospore which Wright describes. The zygozoospores 

 settle on the epidermis of the Lemna, always at the point of junction 

 of two cells. When come to rest they are always already enclosed in 

 a cell-wall. After from one to three days, they begin to penetrate by 

 forcing apart the two cell-walls of the epidermis, and develope into a 

 new individual beneath it. When the host decays or falls to the 

 bottom of the water, these individuals remain in the resting state in 

 which they persist through the winter, and in the spring develope 

 from their contents new zoospores. 



CMorochytrium Knyanum is endophytic in Lemna minor and gihba. 

 The structure and course of development are in the main the same as 

 in C. Lemnce, but the zoospores differ somewhat in shape, and no 

 conjugation of them was observed, either while within the gelatinous 

 envelope or when moving freely in the water. They eventually come 

 to rest, and penetrate the epidermis of the host. They develope into 

 a resting condition within its tissue, and in the spring again develope 

 non-sexual zoospores by bipartition. In addition to the hosts above 

 mentioned, this species was also observed in Ceratophyllum demersum 

 and Elodea canadensis, but never in Lemna trisulca. 



Endosphcera biennis is a hitherto undescribed organism, nearly 

 allied to CMorochytrium, found in the form of large green resting-cells 

 in dead leaves of Potamogeton lucens. The cell-wall is remarkably 

 thick, and evidently composed of two layers ; the contents are proto- 

 plasm coloured by chlorophyll, containing also a colourless oil and 

 numerous small starch-grains, with a clearer space in the centre. 

 When ready to germinate, these divide by repeated bipartition into 

 a number of daughter-cells, each enclosed in a delicate cell-wall 

 of cellulose, the whole at the same time increasing in size. In each 

 of these daughter-cells is now formed, by renewed bipartition, a small 

 number of small spherical zoospores. The whole mass now escapes 

 entire from the host ; the zoospore breaks through the cell-wall of 

 the daughter-sporangia, and the gelatinous envelope of the whole 

 then disappears. The escaped zoospores are pear-shaped, about 

 6 • 2 /Li long and 4 • 9 /x broad, biciliated, and copulate by their apices 

 into a quadriciliated zygozoospore. These invariably perish, unless 



