PROTOCOCCACE. 29 
Famtty II. PROTOCOCCACEA. 
Unicellular algz, in the strictest sense, chlorophyllous, with- 
out terminal growth, or ramification, without a vegetative 
generation of cells, Hither single, segregate, or associated in 
families. Cells of the families either indefinitely increasing in 
number (then forming families) or of a definite number (then 
forming a cenobium). 
Propagation by means of gonidia, arising in the mother cell 
by free cell formation; gonidia of two kinds, the one ‘larger, 
macrogonidia, the other smaller, microgonidia; the former 
oblong, mostly produced anteriorly into a pale bi-ciliate beak, 
rounded and greenish at the posterior end, developing into an 
individual plant; the microgonidia similar to these, and also 
motile, but passing after a short time into a quiescent state, and 
at last into resting spores, or hypnospores. 
This family is usually subdivided into the following sub- 
families :— 
1. Prorococcra. 5. Hypropictye2. 
2. CuLorococcacké. 6. OPHIOCYTIER. 
8. Potyvepriza. 7. PepIastrem, 
4, ScenEDESMEa. 8. SorastREa. 
9. CHARACIER. 
Many of these small sub-families include but a single genus, so that, 
in effect, the character of the sub-family is that of the genus; hence 
they are of little value, especially in a local flora. 
Sub-Family 1. Protococcgs. 
Cells spheroid, segregate; cytioderm thin, hyaline, without 
integument, swimming free, or, when not growing in water, 
forming a thin pulverulent stratum. Contents in the beginning 
homogenous, then granular, green, or reddish. 
Only one genus has yet found a place in this sub-family, of which 
one species is British. 
Genus 22. PROTOCOCCUS. dy. (1824.) 
Characters the same as in the sub-family. Propagation by 
mobile gonidia. 
Protococcus viridis. Ag. Rabh. Alg. 111., 56. 
Cells small, segregate, accumulated in a broadly expanded 
stratum, of a yellowish green colour, either pulverulent, or, 
during moist weather and after rain, somewhat gelatinous. 
Size. Cells ‘0025-004 mm. 
On the trunks of trees, fallen branches, and damp walls 
throughout the year. 
It is very probable that this is only a condition of Pleurococcus vul- 
aris. 
Plate XII. fig. 1. Cells magnified 400 diameters. 
