98 ZYOPHYCE,E. 



" It forms large masses on the water, full of air-bubbles, being pale 

 and yellowish above, and of a blackish green beneath. Filaments not 

 lubricous, nearly equalling those of Spirogyra nitida, but with much 

 longer articulations. When young the colour is of a dull pale green, 

 and about three imperfectly spiral lines of shining granules are with 

 difficulty distinguishable. Afterwards these lines become more con- 

 spicuous, the rest of the filament being now perfectly colourless, and 

 their component granules larger, but their arrangement is still irregular. 

 The filaments subsequently unite here and there, not by every articula- 

 tion, and their connecting processes are usually nearer to one end of the 

 vessicle than to the other. Such filaments are divaricated at the points 

 of connection. In some of the combined articulations the contents 

 appear unchanged, in others they form a mass of larger granules than 

 in the lines, and some have a large oval sporidium which often swells 

 the joint. Some traces of unchanged lines occur, now and then, in the 

 fructifying vessicles." English Botany, 2nd ed., p. 176. 



Plate XL, fig. 1. , sterile c^lls X 200; b, c, d, e, conjugating cells 

 X 200 ; /, zygospore X 400. After De Bary. 



GENUS 47. ZYGOGONIUM. Kwtz. (1843.) 

 Cells cylindrical or barrel-shaped, with a compact, often many- 

 layered glittering cell-wall. On each side near the middle an 

 irregular chlorophyll body, each furnished with a starch granule, 

 both often confluent in an axile string (in the very thick-walled 

 cells usually concealed by granules). Connection of the copu- 

 lating threads ladder-like. The protuberances of the two con- 

 tiguous inter-growing threads that receive the chlorophyll- 

 contents are bounded by partitions into fructifying-cells, which 

 then coalesce into a not-contracted zygospore. 



Zygogonium ericetorum. De Bary Conj. p. 79. 



Sterile cells, 1^- to 2 times as long as broad. 



Zygospores subglobose or oblong, sporoderin rather thick, 

 even. 



SIZE. Cells -013 to -018 mm. diam. Zygospore -013 x '025 

 mm. 



var. a. terrestris. 



Zygogonium ericetorum, Kutz. Tab. v. t. 10, Dickie Bot. Guide, . 

 296. Jenner Fl. Tunb. Wells, 184. Hass. Alg. 174, t. 41, 

 f. 1 , 2. 



Zygogonium torulosum, Kutz. Tab.v. t. 14. 



Conferva ericetorum, Eng. Fl. v. 350 ; Harv. Man. 125 ; 

 Dillw. Conf. 1. 1, Eng. Bot. 1st Ed., t. 1553, 2nd ed. t. 2473. 

 Grev. Fl. Ed. 318. Grev. Crypt. Fl. t. 261 (?) Mack. Hib. 

 224. Fl. Devon, ii. 51. Hook. Fl. Scot. ii. 81. 



Conferva alpina, Eng. Fl. v. 350. Harv. Man. 125. Grev. 

 Sc. Crypt. Fl. t. 261, f. 2. 



On heaths. 



