GANONG ANOXYSCOPE 



Demonstrates the Necessity of Oxygen to Plant Growth 



THE PLANT in the left-hand U-tube receives oxygen, the tube- 

 opening being immersed in water. The oxygen in the right-hand 

 U-tube is absorbed by pyrogallic acid, preventing the growth of 

 the contained plant. 



Price, $4.25 



Our catalog of Ganong Botanical Apparatus completely describes 

 26 different pieces of apparatus. Shall we send^ you a copy ? 



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