ALGAL AND FUNGAL PROTISTS 



29 



If we compare the parasite, A, with a zoospore, G, a 

 great difference in size is apparent, but the protoplast l in A 



FIG. 5. RHODOCHYTRIUM SPILANTHIDIS. A, form of the parasite destined 

 to become a resting spore, rhizoids not in the section ; B, segment of 

 a ripe resting spore, with shrunken nucleus, starch grains, and triple 

 capsule ; G, form of parasite destined to become a zoosporangium, a 

 large vacuole occupies the outer half, and a thickening in the form of 

 a plug closes the surface end ; D, a resting nucleus, a large nucleolus 

 and beads of chromatin on linin threads, from a half-grown zoo- 

 sporangium ; E, the primary mitosis, at one end of the spindle the 

 aster is wanting, and there are coarse linin threads and chromatin 

 masses outside the spindle ; F, the last mitosis and the two last 

 states of subdivision ; G, zoospore ; H } conjugation of two zoospores. 

 Reduced to |, after R. F. Griggs. 



is only slightly larger than that of the zoospore ; the increase 

 in size is due to large vacuoles filled with cell-sap. 



1 The term protoplast in botany signifies the active protoplasmic cell-contents, 

 i.e. the nucleus and cytoplasm of nucleated cells (Hanstein, 1880). 



