EFFECTS OF REGIONS OF VISIBLE SPECTRUM 



783 



the back of the mirror, to the reflecting surface and from there was 



reflected to the inside of the mirror and back to the photocell. The 



same filters were used as have already been mentioned. This method 



cnablod him to take into account the diffusion of the radiation from the 



surface of the leaf. Table 6 gives the average values Seybold obtained 



for transmission, reflection, and absorption at different wave-lengths 



with 10 different species of plants with variegated leaves. Since he used 



filters with comparatively long ranges of transmission, the wave-lengths 



given in this table represent approximately only the maximum point of 



transmission of the filters. 



Table 5. — Transmission of Green and White Sections of VARiECiATEU 



Leaves and of Green Leaves in Different Regions of the 



Spectrum in Percentage of Incident Radiation 



(Approximate spectral ranges of the filters in van., with maximum transmission point 



in parentheses. CuS04 plus BG9 was used with all filters except the white) 



Green leaves 



Tropaeolum majua 



Polygonum Sachaliner.se 



Helianthus annuus 



Phaseolus vulgaris 



Tilia parviflora 



Fraxinua excelsior 



Corylus avellana (shade leaf) 



Corylua avellana (sun leaf) . . . 



Potamogeton alpinus (sub- 

 mersed leaf) 



Potamogeton alpinus (emersed 

 leaf) 



32 

 28 

 20 

 34 

 19 

 20 

 27 

 16 



72 



31 



W. = white; G. = green. 



From these figures it is apparent that light transmission decreases and 

 absorption increases with decreasing wave-length. Absorption is greater 

 throughout in the green portions of leaves than in the white portions, but 



