THE GREEN ALXLE 



629 



the chloroplast is impossible except by a longitudinal division 

 (cf. also Klebs 40, p. 426). In every case the four or eight 

 products of division ultimately become ranged parallel to each 

 other and to the longitudinal axis within the mother-cell. 



Under certain, not yet fully recognised, conditions the pro- 

 ducts of such asexual division are not immediately liberated 

 from one another but remain within the mother-cell and continue 



Fig. 1. 



A-B, Chlamydomonas angulosa. Dill (a, vegetative individual ; B, dividing). c-D, C. longistigma, Dill 

 (stages in division). E, C. Braunii, Gor. (Palmella-stage). F, C. media, Klebs (conjugation). 

 G, C. Braunii, Gor. (conjugation). H, Chlorogonium eucklorum, Ehrbg. I, Brachiomonas suimarina, 

 Bohlin. K, Pkacotus lenticularis, Stein (side-view). L, Polyblephaiis singul-aris, Dang. M, Pyra. 

 mimonas tetrar/iync/i us,Schma.rda.. N, Crypiomonas erosa, Ehrbg. o, Chilomonas Paramecium, 

 Ehrbg. p, Chlorantccba heteromorpha, Bohlin. R, Scenedesmus quadiicauda (Turp.), Bre"b. 

 s, Vacuolaria flagcllata, Senn. (a-d, and M after Dill ; E and G after Goroschankin ; F after Klebs ; 

 h and k after Stein ; i and p after Bohlin ; l after Dangeard ; n and o after Senn ; r after Nageli ; 

 s after Stokes). 



to divide, the walls of the successive mother-cells becoming 

 highly mucilaginous. In this way extensive gelatinous clumps 

 are formed, which are known as Pa/me/la-stages (fig. 1, e). 

 With the return of normal conditions each cell acquires cilia, 

 and, slipping out of the enveloping mucilage, commences an 

 independent existence. Whereas in the majority of species of 

 Chlamydomonas the Palmella-stage is quite a subsidiary phase 



