Te A 
GREEN SLIMES . 171 
235. This phylum has been unusually productive of 
other phyla of primary and secondary rank, and the 
suggestion is hazarded that also from it (near Proto- 
coccoideae) a phyletic line gave rise to the Animal King- 
dom. There are two classes: 
I. Plants unicellular, or in colonies. 
Class 3. PRorococcoIDEAE 
II. Plants pluricellular, in filaments (or plates). 
Class 4. CoNFERVOIDEAE 
3 Cuiass 3. PROTOCOCCOIDEAE. GREEN SLIMEs 
236. These plants (of about 450 species) are nearly all 
microscopic, and are unicellular, or in a few cases aggre- 
gated into definite colonies. They propagate (reproduce 
by asexual reproduction) by (1) cell division, (2) ciliated 
zoospores, (3) and thick-walled spores (chlamydospores), 
and generate (reproduce by sexual reproduction) by the 
union of equal, motile gametes (isogametes) to form a 
single cell (zygote) which often becomes a thick-walled 
spore. Generation is not known for all of the species. 
ORDER PALMELLALES 
237. These unicellular plants are not aggregated into 
colonies, although they may remain attached together 
in irregular masses for some time after cell 
division. They are common in water, and (0) xX 
in moist or wet places, as the sides of walls, 
trees, posts, etc., where they often form Gs) 
dense, green layers. The spherical forms oS cy 
growing on trees, walls, etc., which produce pat be 
no zoospores are species of Protococcus, 
while those with zoospores may be Chlorococcum. 
Near relatives of these have become unicellular para- 
