NO. 13 FUNCTIONS OF RADIATION BRACKETT AND JOII NSTON 



use of the same nutrient solution throughout an entire experiment, 

 the nutritional factors are necessarily identical. 



VIEW or UNDERSIDE SHOWING 



t-. £ - , 1-. t - -t.^-!? 



Fig. 2. — Detailed diagram of plant growth chamber. 



Plate I shows the completed apparatus. The four growth chambers 

 are located in the corner spaces upon a large steel frame. The center 

 space accommodates the central controlling reservoirs. Each chamber 

 is an octagonal cylinder in form, 2.2 inches high by 15 inches in diam- 



