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MISS B. M. BKISTOL OK 



I. ClILOROCHYTmUM LsMNiE, Cohll. 



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This species was estjiLlisheJ by (/olin"^ in 1872, and forms flie basis of tlie 

 genus CMorochytnum. Culm states that the alga is an endophytic green 

 uniccU in which multiplication takes place by means of imnicrous zoogonidia 

 produced by free cell-division, first into lai'ge segments and later into 

 innumerable pear-shaped green bodies which are extruded through the 

 tubular process on the cell-wall. 



Kirchnerf observes that the zoospores are set free sometimes through a 

 split in the ccll-wall into the intercellular spaces of the host, and sometimes 

 through the tubular projection of the wall. 



Klebs X found that tlic spherical, biciliato zoogonidia are formed by a 

 successive bipartition of the green contents of the mother-celb The liberation 

 of the zoospores is etfected by an absorption of water by the mother-cell 

 resulting in a splitting of the cell-wall and of the superposed Lemna tissues, 

 the zoogonidia being extruded through the slit in a mass of mucilage within 

 which they fuse in pairs to form quadricilinte zygospores. The part of the 

 g(UMninating zygospore ronuuning on ihe surface of the leaf is converted into 

 a spherical stopper of cellulose. According to Klebs, the chlorojdast in the 

 young cell forms a continuous parietal layer whiclt, in later stages of 

 development, sends out gr(^en protoplasmic strands to the centre of tlie cell 

 where they anastomose to form a much-branched network. Pyrenoids are 

 present, 



Spencer Moore § suggested that the biciliate gametes might possibly act 

 as facultative zoogonidia, though his evidence was incomplete. 



De Toni || ad<led that the cells vary in size and sha])e, and that eacli 

 contains a single nucleus and disG-shafied chloroplasts ; while AVille % 

 described the cliloroplast as a continuous parietal lajer with internally 

 projecting ledges or rods and containing many pyrenoids. 



In Oct. 191B, and again in Jan. 1917^ a quantity of Lemna trisidca 

 was collected from a pond near Quinton in Worcestershire, and Avas found 



cytology })y means of sections. 



\ 



on examination to contain enough ChlorocJii/trinm Lemnte for a study of its 



The large size of the endophytic cells and 

 the density of their green colour, together with the thickness of the super- 

 posed Lemna tissues, made it impossible to come to any definite conclusions 



♦ Coliu, r, ^^Ueber parnsitisclie Algeii" Beitrage zur Biolog'ie der Pflaiizea, vol. i. 



p. 87. 



t Kirchner, O. .'Die Algen Sclilesicns.' Breslau, 1878. 



X Klebs, G. " Beitrag'c zur Kenntniss uiederer Algenformen." ]?ot. Zeit. xxxix, (1881) 



col. 249-255, pl3. 3,4. 



§ Moore, Spencer. *' Remarks on some endophytic Alg^e." Jonin. of Bot. xxii. (1884) 



pp. 136-138. 



II De Toni, J. B. Sylloge Algarnm, i. pp. 635-C36 (]889). 



% Wille,hN. Die Natiirlichen Pflaczenfamilien, i. Abt. L', p. 66 (1807). 



