CHLOROPHYLL AND HEMOGLOBIN 235 



Another link between chlorophyll and haemoglobin is sup- 

 plied by the fact that Willstatter and Asahina * have obtained 

 from chlorophyll by reduction three pyrrole derivatives : 



C 2 H 5 C = CCH 3 \ C 2 H 5 C = CH \ 



| )NH | )NH >NH 



3 C = CCH 3 / CH 3 C = CH / CH 3 C = CCH 3 / 



Phyllopyrrole Haemopyrrole Iso-haemopyrrole 



one of which, haemopyrrole, has also been obtained by -the 

 reduction of haematoporphyrin. 



With regard to the manner in which the magnesium or iron 

 are respectively united to the complex molecules of chloro- 

 phyll and haemoglobin, the following skeletons, involving the 

 assumption of subsidiary valencies, according to Werner and 

 others, have been suggested f: 



Fe/ 



Chlorophyll Haematin 



In this connexion compare the formula assigned to 

 Aetiophyllin (page 230). 



EXTRACTION OF CHLOROPHYLL. 



The usual method of extracting chlorophyll from green 

 tissues consists in first steeping the fresh material in hot water 

 to destroy oxidizing enzymes and then extracting the colour- 

 ing matter by means of warm alcohol. Willstatter, however, 

 recommends the use of dried in place of fresh material, and 

 extracting by shaking with organic solvents (ethyl or methyl 

 alcohol, ether or acetone) in the cold. 



The chief advantage in using dried material lies in the 

 fact of its relatively small bulk, 100 grams of stinging nettle 

 leaves, for example, weighing only 25 grams after drying. It 

 has been shown, moreover, that the operation of drying pro- 

 duces no change of any importance in the chlorophyll, since 



* Willstatter and Asahina: " Annalen," 1911, 385, 188. 

 f Willstatter and Fritzsche : id., 1909, 371, 33. 



