PURPOSES AND USES OF CHLOROPHYL 1 19 



183. Formation of Chlorophyl in a Blanched Specimen. Place 

 a small artificial light such as might be produced from an oil 

 flame or a few candles, or a single incandescent bulb, in a dark 

 chamber containing etiolated plants and note the formation of 

 chlorophyl. Bring an etiolated plant from the dark room and 

 note the time in which a greenish tinge will be taken on by the 

 leaves. 



184. Microchemical Test for the Presence of Chlorophyl. 

 Secure thin leaves of mosses, or of some aquatic, or mount a 

 thin section of some leaf on a glass slip. Place a drop of satur- 

 ated solution of potassium hydrate in water, on the section and 

 examine with a microscope. Chloroplasts will take on a yellow- 

 ish brown color immediately, which will change to a green tint 

 in the course of half an hour. This change may be hastened by 

 the addition of a drop of glycerine or alcohol run in under the 

 cover-glass. 1 



185. Absorption of Light by Tissues of Plants. A simple dia- 

 phanascope may be made from two shells of cartridges used in 

 shot guns. One should be 10 gauge and the other 12 gauge 

 and should be uncapped. 



Cut circular pieces of leaves of proper size and place over the 

 end of the smaller shell then slip the larger shell over it and hold 

 the instrument toward the sun. Note the amount of light trans- 

 mitted through a single leaf. How many leaves are necessary 

 to exclude the light completely. Test tissues from other parts 

 of the body of the plant. Test the permeability of red leaves. 2 



186. Purposes and Uses of Chlorophyl. Chlorophyl is an ex- 

 tremely complex and unstable substance or group of compounds 



"Molisch, H. Erne neue mikrochemische Reaction auf Chlorophyll. Ber. Deut. 

 Bot. Ges. 14: 16. 1896. 



For the general chemistry of chlorophyl see Marchlewski, Chemie des Chloro- 

 phylls. 1895. And Jour. f. Prakt. Chem. 62 : 247. 1900. 



Etard. Plurality des chlorophylls. Compt. Rend. 120 : 328. 1895. 



Gautier. Sur la plurality des chlorophylls. Compt. Rend. 120 : 355. 1895. 



BLinsbauer, L. Untersuchungen ueber die Durchleuchtung von Laubblattern. 

 Beihefte, Bot. Contralb. 10 : 53. 1901. 



