between that food which is edible and that which 

 is not. 



Further to dwell on the Dinoflagellata would 

 be interesting; much could be detailed regarding 

 the peculiar properties of their "cold" and phos- 

 phorescent light; a chapter could scarce contain all 

 that might be said about their achievement of 

 immortality, wherein the adults never die a "nat- 

 ural" death but translate their identity by divid- 

 ing into daughter twins; nor would their haunts 

 and habits fail to hold our attention for a while; 

 but our notice of Noctiluca and others of its kind 

 must necessarily be brief, for I have still other 

 slides to see. 



Also in the D section come the diatoms. Unlike 

 the slide I have just considered, the one now 

 selected fails under the most careful scrutiny to 

 disclose anything to the unaided sight. The cir- 

 cular area occupied by the cover-glass under which 

 the objects are cemented to the slide, has every 

 appearance of being nothing else than the most 

 transparent glass. And yet within the diameter of 

 this circle, the diameter of which does not exceed 

 a fourth of an inch, there are loosely dispersed 



fn7] 



