Smithsonian Report. 1931. — Matheson 



Plate 6 



A, Wooden tiiiiksiiividcil iiit()C(]mii;irtimMits td test ( 'hnra frayilis in still and running 

 water; B, a deep woodland pool in which Chara fragilis was introduced; C, a 

 spring-fed pool (Hullerniilk Kails I'oolj ])lanted with Chara fragilis 



