PolybfapTiaridacese 



16i3 



Multiplication takes place by longitudinal fission, in some forms com- 

 mencing at the anterior and in others at the posterior extremity. Resting- 

 cells are formed by the direct encystment of the motile individuals. Gametes 

 of a more or less isogamous character occur in Dunaliella (Teodoresco, '05), 

 and they fuse in pairs to form zygotes. 



The most primitive genus of the family is Polyblephcvrides, in which the body of the 

 cell is conical with a broad anterior end to which are attached from six to eight cilia. In 

 Pyramimonas, which possesses only four cilia, the cell-body is also more or less conical, 

 and is four-lobed in the anterior region. Chloraster, which is furnished with five cilia, is 



Fig. 95. A E, Dunaliella salina (Dunal) Teodoresco ; A and B, normal form of zoogonidia 

 ( = vegetative cells) ; C and D, stages in division, in D the second cilium making its 

 appearance ; E, single cell showing detailed structure. F I, Pyramimonas delicatulus 

 Griffiths ; F, vegetative cell ; G, beginning of longitudinal fission, the pyrenoid having 

 divided and 8 cilia developed ; H, peculiar blistering and disintegration of cell on treatment 

 with 4 per cent, formalin, showing swelling of cilia at their extremities ; 7, anterior axial 

 view of H at an earlier stage in disintegration showing lobed chloroplast. c, cilia ; 

 n, nucleus; pc, posterior excavation of chloroplast; pt, protoplasmic membrane; pi/, 

 P3'renoid ; s, minute grains of starch ; t , plasmatic thread from nucleus to base of cilia. 

 A D, after Teodoresco, x 1000 ; E, after Hamburger, x 2250 ; F H, after Griffiths, 

 x800. 



much more prominently four-lobed in the middle region of the cell-body ; and the biciliated 

 Asteromonas has the cell-body extended into six rounded ridges which run antero-posteriorly 

 and have their greatest development in the median part of the cell. 



Dunaliella possesses only two cilia and is in every way the nearest approach to the 

 Chlamydomonads. Stephanoptera, recently described by Dangeard ('10) is very similar to 

 Pyramimonas, but is only furnished with two cilia. It is thus a natural connecting-link 

 between Pyramimonas and Dunaliella. 



The genera included in this family are : Polyblepharides Dangeard, 1887 ; C hlo raxb'.r 

 Ehrenberg, 1848 ; Pyramimonas Schwarda, 1850 ; Tetratoma Biitschli, 1887 ; Dunaliella 

 Teodoresco, 1905 ; Stephanoptera Dangeard, 1910 ; Asteromonas Artari, 1913; Spermato- 

 Korschikoff, 1913. 



