Normal Light Screen 



for the study of 



Photosynthesis 



This screen, designed by Professor Ganong, is correct 

 in princii)le, allowing for the free access and exit of gases. 



It takes an entire leaf of moderate size. 



List price, $10.00. Smaller screens for the use 

 of individual students, $ 1 . 25. 



Catalog of Ganong Botanical Apparatus will be sent 

 on request. 



Bausch ^ Ipmb Optical (g. 



NEW YORK WASHINGTON CHICAGO SAN FRANCISCO 



LONDON lioCHESTEn, N.Y. •^Rankfort 



