148 LIVING PLANTS 



demonstrated. In order to do this a solution 

 of the substance is obtained by placing a 

 gram of chopped leaves of grass or geran- 

 ium in a few cubic centimeters of alcohol for 

 an hour. The solution will be a bright, clear 

 green color, and when the vessel containing it 

 is held in such a manner that the sunlight is 

 Properties of reflected from the surface of the liquid it will 

 chlorophyll appear blood-red, due to its property of ^i/or- 

 escence, that of changing the wave lengths of 

 the violet end of the spectrum in such a man- 

 ner as to make them coincide with those of 

 the red end. It is by examination of light 

 which has passed through a solution of chlor- 

 ophyll, however, that the greatest insight 

 into its physical properties may be obtained. 

 If such a ray is passed through a prism and 

 spread upon a screen, it may be seen that 

 therfe are several intervals of dark bands in 

 the spectrum. The rays which would have 

 occupied these spaces have been absorbed by 

 the chlorophyll and converted into heat and 

 other forms of energy. This energy is directly 

 available to the protoplasm containing the 

 chlorophyll. As a necessary concomitant of 

 its physical properties, chlorophyll is usually 

 only to be found in organs exposed to the 

 light. It would not only be useless but dan- 

 gerous elsewhere, as it disintegrates in dark- 

 ness into substances hurtful to the organism. 



