148 VEGETABLE PHYSIOLOGY 
chlorophyll absorbs these particular rays of ight which are 
missing. 
In fig. $4 is a representation of the spectrum which 
such treatment produces and which is called, from the facts 
just narrated, the absorption spectrum of chlorophyll. The 
uppermost figure is that which is exhibited by an alcoholic 
solution or extract of leaves; the middle one is given by 
chlorophyll dissolved in benzol. The first band on the left 
is the darkest, and is found to be in the red part of the spec- 
trum. ‘he three bands on the right are broader, but are 
Et F G 
BO} 0 50. 60 ie 700 
ee a 
| 
1 ut ] Tl 
\ i HN i) 
| il il y Hl 
\ ll HH Il 
I i | J M 
4 ' ie 50 60 i 20 100 
yt 
thi 
3001 40 
Laid | 
Ii W@W WV 
lia. 84.—ABsoRPTION SPECTRA OF CHLOROPHYLL AND 
XANTHOPHYLL. (After Kraus.) 
not so well defined. They cover nearly all the blue end. 
The three thinner and lighter bands are in the yellow and 
green parts of the spectrum. Chlorophyll therefore has 
the power of absorbing a large number of red rays, a good 
many blue and violet ones, and a few of the green and yellow. 
The distinctness with which these absorption bands are 
seen depends upon the strength of the solution, those in the 
red and blue being, however, always prominent. Careful 
experiments have proved that chlorophyll is a single pigment 
and not a mixture of two, as has often been stated. Tt is, 
however, easily decomposed, and the products of its decom: 
