DIATOMACE.E 



193 



after successive divisions of the same kind, and 

 always in the same direction, form a chain. Since 



Hi 



d 



FIG. 5P. Pinnularia viridis. a, valve view ; b, pirdle view ; c, the new 

 valve has forced the girdle apart highly magnified ; d, diagram of successive 

 divisions of a Diatom, (a, b, d, after Pfitzer.) (P. viridis is a fresh-water form.) 



every fresh division leads to the formation of new 

 valves, the edges of which are within the girdle of 



o 



