RECENT EBSEARCHES IN THE DIATOMACEiE. 389 



opportunity of observing in a living state is S. cruciger, and 

 in this the circumstances of the movement and division of 

 the endochrome plates were just as in Navicula. 



In Colletonema subcoh<2rens, according to the observation 

 of Thwaites, two mother-cells produce two auxospores, and 

 the process occurs occasionally outside the gelatinous tube. 

 In Schizonema Grevillii, according to Smith, one mother-cell 

 produces one auxospore, but according to Liiders this is 

 abnormal, and occurs only when one of the auxospores 

 withers off, the general rule being that two cells co-operate 

 to produce two auxospores. 



