FROTOCOCCACE.E. 



29 



FAMILY II. PROTOCOCCACE^E. 



Unicellular alga?, in the strictest sense, chlorophyllous, with- 

 out terminal growth, or ramification, without a vegetative 

 generation of cells. Either 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 ccenobiiun}. 



Propagation by means of gonidia, arising in the mother coll 

 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. PROTOCOCCE^:. 5. HYDRODICTYE^E. 



2. CHLOROCOCCACE^E. 6. OPHIOCYTIE.E. 



3. POLYEDRIE.E. 7. PEDIASTRE.E. 



4. ScENEDESMEiE. 8. SoRASTRE^E. 



9. CHARACIE.E. 



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. PROTOCOCCEJ:. 



Cells sphseroid, 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. FROTOCOCCUS. Ag. (1824.) 

 Characters the same as in the sub-family. Propagation by 

 mobile gonidia. 



Fxotococcus vixidis. Ag. Rabli. Alg. in., 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- 

 ga, ris. 



Plate XII. Jig. 1. Cells magnified 400 diameters. 



