l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Plate 3 



General arrangement of cultures in experiment 8 on rotating tables placed 

 about the two light sources. The Mazda lamp encased in a water jacket is on 

 the left and the 400-watt mercury lamp on the right. The small rotating tables 

 turned at the rate of 3.4 r.p.m. This prevented phototropic curvature of the 

 stems but not of the leaves which, although turgid, appear wilted. 



Plate 4 



Tomato plants grown for 21 days under the following intensities (watts/cm*). 

 Daily illumination was 18 hours. 



Mazda Mercury 



Culture (water-cooled) (400 watts) 



1 0071 .0048 



2 0071 .0047 



3 0140 .0046 



4 0144 .0045 



5 0137 .0010 



6 0146 .0010 



