202 CHYTRIDIE^E. 



GENUS 80. CHLOROCHYTRIUTO. Colin. 



Plant endophytic ; green, unicellular ; cells globose, or some- 

 what irregularly bi-, tri-, or multi-lobed ; densely filled with 

 chlorophyll, first dividing into large segments, and then these 

 giving origin to innumerable pyriform zoospores, which escape 

 through a tubular process. 



Chloxochytxium Lemnse. Cohn. Beitr. I., 87. 



The zoospores, impinging on the epidermis of the duckweed 

 at the junction of two cells, after germination commences a tube 

 is produced, which, entering between the walls of the dissepi- 

 ments, proceeds as far as the mesophyllic parenchyma, growing 

 into the intercellular spaces, and forms either a globose, 

 elongated, or irregular-shaped cell. 



SIZE. Adult cell O-'l mm. diam. 



Wright in Trans. Roy. Irish Acad. xxvi. (1877), p. 13. 

 Archer in Quart. Journ. Micr. Sci. xv. (1875), p. 104. 



Living in the thallus of Lemna trisulca. Westmeath (Ire- 

 land). 



Cohn says of this species : " Its zoospores attach themselves to the 

 thallus of the duckweed often in hundreds. They force tbeir way 

 through between the epidermal cells, assuming, as the foremost portion 

 gets into the hypodermal tissues, a more or less figure of eight-shaped 

 form : the foremost portion, getting into an intercellular space, dilates ; 

 the portion that has not entered remains unexpanded, and forms a 

 colourless nipple-like projection ; the portion within the thallus expands 

 to many times its original diameter, sometimes dilating and filling up an 

 intercellular space, at others distorting the subadjacent cellular tissue, 

 and frequently itself becoming variously distorted. The cell wall becomes 

 thicker, even laminated ; the chlorophyll contents get dark and dense, 

 and the cell becomes of a dark, nearly opaque green ; sometimes starch 

 granules are seen. The cell contents become segmented, breaking up into 

 a number of pear-shaped zoospores, which escape through the nipple-like 

 projection ; their actual exit was not seen, nor was the number or position 

 of the cilia observed. Of the zoospores, many never succeeded in pene- 

 trating the epidermis of the duckweed upon which they alighted, and 

 such would remain as minute colourless pin's heads on the surface of the 

 Lemna. Some would linger within the mother cell, and might possibly 

 be resting spores." Abstract by Prof. Perceval Wright, loc. cit. 



Plate LXXXI. fig. 9. Chlorochytrium Lemnte parasitic on duckweed. 

 Zoospores located in intercellular spaces X 600. Fig. 10, in a more 

 advanced stage x 600. Fig. 11, free zoospores x 600. After Cohn. 



