550 THE PATHOGENIC ALGAE. 



The zoospores (gametes) copulate in the gelatinous mass which 

 escapes, and break out from it as free swarming zygozoospores. 

 When the Lninin falls to the bottom in autumn, or when it 

 dries up, the cells of the alga become resting-cells capable of 

 sustaining drought. Plants of Lcmna seem to be little 

 disturbed by attacks of the endophyte, and develop their 

 flowers normally. 



Chi. Knyanum Kirchn.- Frequents Lcmna minor and L. gibba, 

 Ccratoplnjlhim demcrsum, Elodea canadcnsis, but not Lemna 

 trisulca. It forms zoospores only, and these on penetrating 

 into a host do not produce a cellulose button like the species 

 just described. They appear to be able to enter the host only 

 by the stonmta. 



Chi. pallidum Klebs. Grows in the intercellular spaces of 

 Lemna trisiilca. 



Chi. viride Schroet. Found in the respiratory cavity of 

 If n. m ex obtusifuli >/ s. 



Other species occur in dead Phanerogams or in Algae. 



Stomatochytrium limnan- 

 themum Cunningh. Inhabits 

 the respiratory cavity of leaves 

 of Limnanthemum indicum in 

 India, 



Chlorocystis Cohnii Reinh. 

 ( )ccurs as a " shelter-parasite " 



Fio. 326. Bndosphaem biennis in Potamogeton jj| marine 

 lucens. Cell of the Alga, which has penetrated 



through the epidermis a few weeks previously. SCOtlllOSphaera 



(After Klebs.) r 



Klebs. Found between the 

 cells of dying leaves of Hypnum and Lcmna triscula. 



Endosphaera biennis Klebs. The zygozoospores have four 

 cilia, and swarm in water till they reach a living leaf of 

 Potamoycton lucens. They generally come to rest on the under- 

 side of a leaf at the boundary wall between two cells, and 

 become invested in a membrane. A process is next sent in 

 between the epidermal cells, and all the cell-contents pass over 

 into it, the outer portion dying away. The young alga now 

 makes its way into the intercellular spaces of the sub-epidermal 

 tissue and becomes a resting spore. In spring this spore 

 gives off biciliate gametes, which, after copulating, become 

 zygozoospores. This shelter-parasite has not yet been observed 



