188 



Chlorophycece 



species of this genus, but Chi. Kleinii Schmidle (length of cell 28 32 p. ; 



breadth 8 12 /*; fig. 73 J and K), Chi. De Baryana Gorosch. (breadth 12 



20 /* ; fig. 73 H and I) and Chi. 

 pulvisculus Ehrenb. ( = Chl. 

 JHhrenbergiiQoroscln. ; breadth 

 14 26 p.) are not uncommon 

 in ponds, ditches and rain- 

 pools. 



Concerning Chlamydomo- 

 nas Blackman and Tansley 1 

 write, "This genus holds a 

 unique position among the 

 Green Algae,and indeed among 

 the whole of the Green Plants. 

 It may be regarded as the 

 phylogenetic starting point of 

 the various lines of Chloro- 

 phyceous descent. The history 

 of these is a history of the 

 intercalation of a vegetative 

 phase between two successive 

 motile (Chlamydomonadine) 

 generations, these motile 

 phases being retained for re- 

 productive purposes as zoo- 

 spores and gametes ; in the 

 oogamous types the male 

 gamete alone remains motile, 



K 



H l 



Fig. 73. A G, Carteria multifilis (Fresen.) 

 Dill, from Bradford, W. Yorks. A and B, 

 vegetative cells; D, gametes; E, conjugating 

 gametes; F, zygospore. H and I, Chlamydo- 

 monas De Baryana Gorosch., from St Just, 

 Cornwall. J and K, Chi. Kleinii Schmidle, 

 from Uxbridge, Middlesex (All x 475). cv, con- 

 tractile vacuoles; n, nucleus; p, pyrenoid; 

 zg, gamete; z, zygospore. 



and constitutes in the Arche- 



goniate series the last remaining representative of the Chlamydomoiiadine 

 cell. 



" The co-existence within the limits of an undoubtedly natural genus of 

 the most primitive form of gamogenesis (the conjugation of equal clothed 

 gametes) with a gamogenesis which has the essential characteristics of true 

 oogamy is also a feature of unique interest." 



Genus Chlorogonium Ehrenb., 1830. The vegetative cells 

 are fusiform, three or more times longer than the diameter, with a 

 thin cell- wall closely adhering to the body. There are two cilia 

 attached to the anterior extremity and a number of contractile 

 vacuoles scattered through the protoplasm. The chloroplast is ill- 

 defined, spongy and anastomosing in character, and contains four 

 or five, or sometimes many pyrenoids. Franc6 describes the chloro- 

 plast as forming a regular or irregular annular band, which may 

 split into a single or double spiral. Reproduction takes place by 



1 Blackman & Tansley in The New Phytologist, 1902, vol. 1, pp. 23, 24. 



