Apr. 1896.] BOTANICAL SOCIETY OF EDINBUKGH. 537 



chlorophyll has been almost universally admitted. The 

 point of dispute is whether there is only one or several 

 such lipochromes. Hansen's experiment was to extract 

 green leaves with alcohol, and shake up the extract with 

 benzol. If the experiment be performed with care, a 

 separation into two layers takes place, the benzol taking 

 up the chlorophyll-green, and leaving the yellow lipo- 

 chrome in the alcohol. To this lipochrome the name 

 of chlorophyll-yellow, or xauthophyll, has been given. 

 As Dr. Schunck (14) points out, however, it is impossible 

 by such means to produce a chemically pure product, so 

 that conclusions based only upon the results of the 

 investigation of this alcoholic solution are not absolutely 

 reliable. Be this as it may, the beauty and simplicity 

 of the experiment have determined its persistence, and 

 xanthophyll has found its way into all the more recent 

 text-books. The probable existence of another lipochrome 

 in connection with the chlorophyll of leaves, is shown by 

 the following experiment, which is almost as simple. Boil 

 green leaves with strong alcohol and filter hot, on standing 

 in the dark the filtrate deposits a dark greenish pre- 

 cipitate, consisting of fats, impurities, a lipochrome, and a 

 greater or less amount of (modified) chlorophyll-green, 

 according to the time the solution is allowed to stand, 

 and the degree of its concentration. The lipochrome 

 frequently occurs in the form of reddish crystals. As 

 might be assumed from its method of precipitation, it is 

 little soluble in cold alcohol, but is readily soluble in 

 chloroform, and can be easily obtained in pure crystalline 

 condition. This experiment has been performed by many 

 investigators, notably by Macchiati and Schunck, but 

 usually only as part of the method of chlorophyll purifica- 

 tion. Macchiati (11) washed his leaves with alcohol 

 and ether before extracting with alcohol, and thus 

 obtained on cooling a precipitate of nearly pure lipo- 

 chrome (mixed with some modified chlorophyll-green ? ). 

 He then removed the lipochrome by filtration, and 

 succeeded in obtaining crystals of so-called " pure 

 chlorophyll " by concentrating the filtrate. These 

 crystals, when dissolved in alcohol, give Hansen's re- 

 action with benzol, and undoubtedly consisted of a 



TRANS. BOT. SOC. EDIN. VOL. XX. 2 M 



