SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 92, NO. 6, PL. 1 



1. Water Baths in Which the Flasks of Algae are Immersed 



Each flask of algae is enclosed in a container with a light filter on the bottom. Conditions of 

 light, temperature, and humidity are controlled alike in all four baths. 



2. Nephelometer Employed for Quantitative Transmission 



Measurements to determine the comparative 



Amounts of Growth of Algae 



