364 



Conjugate 



several parietal cushion-like chloroplasts in each semicell, but the parietal 

 disposition is not constant. In many species the chloroplasts are very variable 

 in character and disposition, numerous intermediate states existing between 



B 



Fig. 221. A , Pleurotsenium trocMscum 

 W. & G. S. West. B, PL doliiforme 

 W. & G. S. West. Both x 433. 



Fig. 22$. A, Euastrum oblongum (Grev.) Kalfs 

 showing the mucilage secreted from one ex- 

 tremity of the cell, x 405 (after Schroder). 

 B, St.niiriixtrumcuspidatum'Br&'b.v&r. maximum 

 W. & G. S. West, x 360. C, St. subpyginaum 

 W. West, x 468. D and E, Arthrodesmus 

 Incus (Breb.) Hass. var. RaJfsii W. & G. S. 

 West forma latiuscula, x 450. 



the truly axile and truly parietal conditions. This is especially noticeable 

 in certain species of Xanthidium, in Staurastrum grande Bulnh. and St. brasi- 

 liense Nordst. var. Lvndellii (vide W. & G. S. W., '04 '11). There is little 



