DIATOM MOTION. 



139 



Figure VI, B. Navicida gibba, Kutz. 



POSITION 



I 

 2 



3 

 4 

 5 

 6 



7 

 8 



9 

 10 

 1 1 



riMp: 

 32 

 33 

 34 



35;^ 



36 



37 



38 



39 ^'^ 



41 



42 



42;<( 



Disappeared. 

 Returned. 



Disappeared. 

 Returned. 

 Reversed motion. 



Disappeared, and did not return after 2] 

 minutes. 



