Smithsonian Report, 1931. — Matheson 



Plate 2 



1. Ajjiiuiiiluh fur tosiiiiK the effect of oxygen on larvae. Two cylinders 

 are being treated while two others serve as controls 



2. A small portion of a branch of Utricvlaria vulgaris. Ten active 

 bladders are shown and five of them contain mosquito larvae. 

 Magnified seven times 



