Comparative Study of Chloo'ophyll. 405 



made out. At the red end of the spectrum we have general 

 absorption, also commencing rather abruptly at X 712. 



B. Two leaves placed together and examined showed — 



1. A dark band at \ 692 [centre at X 674] - X 6621. 



2. A paler band from X 662-1 -X 637. 



8. General absorption, commencing at X 506"3. 



C. Four leaves laid together showed — 



1. A dark band, X 675 - X 642. 



2. A doubtful absorption, its centre about X 62S. 



3. Very faint absorption, its centre at X 579. 



4. General absorption, commencing at X 523. 



The three sets of spectra just described were got when 

 experimenting with rather old leaves, on which the veins 

 had assumed a dark-brown colour. If a single young leaf 

 be taken, in which the veins at the base of the leaf only 

 have a dark colour, we get a spectrum similar to that de- 

 scribed above, where two leaves were taken. The reason is 

 that the leaves gradually become paler and more transparent 

 as they grow older. 



The absorption-spectrum of a young leaf is the follow- 

 ing: — 



1. Dark band : X 695 [centre = X 672] -X 661. 



2. Pale band : X 649 [centre = X 643] - X 636. 



3. Absorption at blue end commences at X 518. 



1. Dark band : X 694 - X 677 . _ ^ , ^ 



2. Paler band: X 650 -X 648 ^ - ^^^^^ ^^ 



The absorption-spectrum of living chlorophyll in Triclio- 

 mancs would be therefore approximately — 



3. Very pale absorption, with centre about X 628 = 



Kraus' II. 



4. A more marked absorption, its centre about 



X 579 = Kraus' III. 



5. A faint band : X 490-5 - X 469-5 = Kraus' V. 



6. General absorption commencing at X 446-3. 



D. An alcoholic extract, made by triturating two young 

 leaves for twenty minutes with 50 c.cm. of absolute alcohol, 

 gave a very pale green solution, with the following bands : — 



