THE FOOD OF PLANTS. 



troublesome to make. 

 The fresh solution, 

 prepared in the dark, 

 is poured into small 

 glass bottles with par- 

 allel plane walls, and 

 tightly-fitting stoppers, 

 which may be ob- 

 tained from Muencke, 

 Berlin. These bottles 

 are simply placed on 

 the stage of the micro- 

 scope, and we then 

 study the spectrum. 

 The chlorophyll spec- 

 trum exhibits seven 

 absorption bands, as 

 represented in Fig. 8. 

 In particular, the band 

 in the red is very 

 characteristic, and can 

 still be seen even with 

 very dilute solutions. 

 If we use fairly con- 

 centrated solutions, the 

 bands I.-IV. still stand 

 out distinctly, but the 

 bands V., VI., and 

 VII. are merged into a 

 single end absorption. 

 To see them, also, we 

 must work with more 

 dilute solutions, and 

 employ direct sunlight. 

 The results of the ob- 

 servations are to be 

 noted on a scale on 

 which the position of 

 the Frauenhofer's lines 

 is indicated. In exact 

 investigations we 



FIG. 6. Microscope with complete microspectroscope. 



