BY G. I. PLAYFAIR. 495 



■JFig. 6. —Result of fifth division; 6a is practically Micr. oscitans P»,alfs, 

 f. minor. 



Fig3.7-S. — Lateral lobules of Micr. truncata vnr.decemdeniata developing 

 into the type by growth of additional spines and cleavage of lobules. 



Figs. 9-10. — Examples of continuous division, halves of 4-celled chains {six 

 immature semicells with a more mature semicell at each end); (9) 

 in Ar. triangularis; (10) in Micr. truncata var. decerndentata. 



Fig. 11.— Part of a very long chain of degenerate cells of Docidium traheeula 

 produced by continuous division. The cell A+B has divided a 

 second time before B has completed its previous division, being not 

 yet cut off by a septum. The chloroplasts were continuous through 

 three semicells. All these four cells were alive, and joined into a 

 chain, as marked. 



