114 CHLOROPHYLLINE CHROMULES. 



ON THE ABSORPTION SPECTRA OF CHLOROPHYLLINE 

 CHROMULES* 



By N. Peingsheim. 



From a somewhat extensive series of experiments on Chlorophyll, the 

 author has here collected some results obtained from the optical exami- 

 nation of those yellow chromules, which, besides chlorophyll, or as 

 representing it, are generally diffused throughout the leaves and flowers 

 of plants. 



The phenomena of absoi-ption and fluorescence peculiar to these 

 chromules are imperfectly known. Their spectra, however, show a 

 very noteworthy agreement with that of chlorophyll. This agree- 

 ment, hitherto overlooked, reveals the close affinity of these chromules 

 to chlorophyll, and leads to rather important physiological inferences, 

 which being only indicated here will be further carried out and estab- 

 lished in future communications. 



The author divides his subject into the following heads: — I. The 

 yellow chromule of etiolated plants. II. The chromule of yellow 

 blossoms, with appended remarks on the spectrum of the yellow 

 chromule of autumn leaves. III. The yellow ingredient in the green 

 leaf (chlorophyll). 



The following is the substance of these investigations : — 



I. The yellow chromule of etiolated plants. 



Plants grown in the dark, more particularly Angiosperms, do not 

 become green, and so it has been generally supposed that chlorophyll 

 is developed under the influence of light. If, however, plants 

 develop for some time in the dark, they do not appear colourless, but 

 intensely yellow. 



The relations between this yellow chromule and chlorophyll are 

 not yet known ; and although it may seem natural to suppose when 

 etiolated plants become green on exposure to the light that it is this 

 yellow chromule which changes to chlorophyll, still no facts have 

 yet been brought forward to warrant such a conclusion. 



The optical characteristics of chlorophyll, its monochromatic 

 fluorescence, and very peculiar spectrum of absorption easily distin- 

 guish it from other chromules. There exist, however, several modifi- 

 cations of chlorophyll. I wish now to confine myself to those 

 properties of the chlorophyll-spectrum vrhich are directly involved in 

 a comparison with the other spectra to be discussed. I refer particularly 

 to the seven known dark bands in the chlorophyll spectrum correspond- 

 ing to the regions of greater absorption ; and as usual I count them 

 as they appear in an alcoholic solution in the direction from red to 

 violet. 



It is important to notice the relative amount of absorption in the 

 darkened regions of the several forms of chlorophyll as indicated by the 

 order in which the bands of absorption become visible according as 

 the amount of chlorophyll contained in the layer increases. 



♦ The term " chromule " is used throughout in the general sense of colouring 

 matter. 



