204 



BINARY SUBDIVISION OF DESMIDIACE.E. 



of its separation (f) acquires the characteristic notched outline of 

 its type, being only distinguishable from the older half by its 

 smaller size. The whole of this process may take place within three 

 hours and a half.* — In Sphcerozosma, the cells thus produced 

 remain connected in rows within a gelatinous sheath, like those 

 of Didymoprium (Fig. 115) ; and different stages of the process 



Fig. 112. 



Binary Subdivision of MicrasUrias denticulata. 



may commonly be observed in the different parts of any one of the 

 filaments thus formed. In any such filament, it is obvious that 

 the two oldest segments are found at its opposite extremities, and 

 that each subdivision of the intermediate cells must carry them 



* See Lobb in "Transact, of Microsc. Society," n.s., Vol. ix. (1861), p. 1. 



