EUPHYCOPHYTA 4I 



be motile and became attached. The ellipsoidal cells occur singly, 

 or in aggregates on submerged plants or living aquatic larvae, being 

 borne on a short stalk that emerges from a small basal disc. In most 

 species the mature cells contain more than one nucleus. Asexual 

 reproduction is by means of biflagellate zoospores which are 

 liberated through a terminal or lateral aperture. Sexual reproduc- 

 tion is generally isogamous but some species exhibit anisogamy. 

 In C. saccatum the + and - gametes are produced from separate 



Fig. 16 Characium angustatum. A, vegetative cells ( x 650). B, cell 



commencing zoospore formation ( x 650), C, liberation of zoospores : 



the cell is probably broken accidentally ( x 650). (After Smith.) 



plants. They fuse to give a zygote and this, on germination, divides 

 to produce a number of zoospores. The aUied marine algal endo- 

 phyte genus Codiolum is interesting because one of the species, C. 

 petrocelidis (found in the red encrusting alga Petrocelis) has recently 

 been shown to be a phase in the Ufe cycle of a larger green alga 

 Spongomorpha (cf. p. 87). Another species, C. kuckuckii occurs in 

 the brown alga Splachnidium and it remains to be seen whether 

 this too is but a phase in the life cycle of another alga. 



Endosphaeraceae : Chlorochytrium {chloro, green; chytrium, vessel). 

 Fig. 17 



The species grow endophytically in other plants such as mosses, 

 angiosperms and red algae. The cells are spherical or ellipsoidal, 

 the walls varying in thickness. Reproduction is by means of bi- 

 flagellate gametes that normally fuse to give a motile zygote. This 



D 



