228 



ASSIMILATION 



mum assimilation, the former placing this in the orange red, where 

 the darkest absorption band of chlorophyll actually occurs ; the latter 

 on the greenish side of the yellow, where the rays brightest to the 

 eye occur. The former diagram is probably the more correct. 



FIG. 6. Assimilation of carbon and chlorophyll absorption. 



In connection with the action of light upon plants, it may be 

 pointed out that though light of low refrangibility (i.e., near the red end 

 of the spectrum) is undoubtedly most active in promoting carbon as- 

 similation, yet light of short wave length (i.e., from the violet end of 



ABCD EF G H 



BED I ORANGE | YELL /w | GREEN | BLUE | VIOLET | 

 FIG. 7. Distribution of assimilatory power, light, heat and chemical action. 



the spectrum) is of most importance in directing the motion of the 

 leaves or of affecting the growth in length of the shoots. 



With reference to our knowledge of the method by which the 



carbon ^dioxide of the atmosphere is brought into contact with the 



