8 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Experiment 7. — An experiment varying a little from the one just 

 described was next performed. In this, five cultures of tomato seed- 

 lings were placed around the Mazda lamp at positions which gave 

 them approximately equal light intensities from this lamp. A sixth 

 culture was located at a position where the Mazda intensity was about 

 half that of the other cultures. The intensities of each of the two 

 lamps for each culture of these plants are best seen in table 6. 



After 18 days the plants were harvested and their dry weights 

 determined. The plant data appear in tables 7 and 8. 



Table 6. — Radiation measurements^ from experiment 7 



Foot-candles with 



Watts/cm^ small G. E. meter 



Culture , *- V , * , 



no. Mazda Hg Total Mazda Hg Total 



1 0234 .0097 .0331 1,300 2,000 3,300 



2 0241 .0018 .0259 1,300 300 1,600 



3 0241 .0013 .0254 1,400 200 1,600 



4 0240 .0013 .0253 1,400 200 1,700 



5 0231 .0039 .0270 1,300 600 1,900 



6 0II2 .0090 .0202 600 1,900 2,500 



^ Since the original Mazda lamp was replaced after 6 days, these measurements were made 

 on the second lamp on the loth day of the experiment. 



Table 7, — Stem height (cm) data from experiment 7 



Culture number 



. A 



Plant 1234 



a 16.5 16.2 19.0 18.5 



b 15-8 18.0 15.5 22.3 



c 14.5 19.4 19.0 20.0 



Av. ht. at harvest 15.6 17.9 17.8 20.3 



Av. original ht 2.3 2.1 2.2 1.6 



Av. increase in ht 13.3 15.8 15.6 18.7 



19.9 



17-5 



Table 8. — Average green and dry weights (grams) of plants from 

 experiment 7 



Culture Green wt. 



no. Tops 



1 6.1 



2 4.2 



3 4-8 



4 5.8 



5 6.6 



6 6.3 



Tops 

 •713 

 •311 

 ■391 

 .467 

 .582 

 .610 



Dry wt. 



Roots 

 .199 

 .044 

 .060 

 .064 

 .099 



.145 



Total 

 .912 



•355 

 .451 

 •531 

 .681 



•755 



