FLUORESCENCE OF CHLOROPHYL SOLUTIONS 121 



the chloroplasts in any plant is always decreased by the opacity 

 of the outer membranes. Beyond this however, it is found that 

 the amount of light absorbed does not correspond exactly with 

 the amount of photosynthesis. 



188. Fluorescence of Chlorophyl Solutions. Place 100 grams 

 of freshly chopped young leaves of any convenient species, the 

 sap of which gives a neutral or alkaline test with litmus paper, 

 in an evaporating dish and cover with distilled water. Boil for 



FIG. 58. Abs. green, curve showing amount of energy absorbed from different 

 portions of the spectrum by green chloroplasts. Ass. green, amount of photosynthesis' 

 in same portions. Abs. red, curve of absorption by red alage. Ass. red, amount of 

 photosynthesis in corresponding portions of the spectrum. Engelmann, after PfefTer. 



half an hour. Pour off the water and wash repeatedly in dis- 

 tilled water. Squeeze out the last of the water and place the 

 material in a closed flask and cover with 500 cc. alcohol (95 per- 

 cent.). Set in a dark place and shake occasionally. A service- 

 able solution of chlorophyl will be obtained in a few hours. 

 Decant some of the solution into a narrow test-tube, and hold be- 

 tween the eye and a strong light at various angles until a blood- 

 red fluorescence can be seen at the edge of the solution. The 

 effect may be heightened if the test is made in a dark room and 

 a small beam of daylight admitted. This fluorescence is due to 



