THE 
MONTHLY MICROSCOPICAL JOURNAL. 
MAY-1, 1877. 
I.—The various Changes caused on the Spectrum by different 
Vegetable Colowring Matters. By Taos. Patumr, B.Sc. 
(Read before the Royau Microscoricau Society, April 4, 1877.) 
Puate CLXXIX. 
Tue kind reception that I met at your hands on a former occasion 
has encouraged me to trespass this evening for a short time on 
your forbearance, while I lay before you the result of some observa- 
tions that I have lately been making on the variability of the 
chlorophyll band in the spectrum. 
Chlorophyll, Fxcula viridis, or leaf green, is the name gene- 
rally given to the green colouring matter of vegetables ; it is found 
in nearly all plants growing in the light, with the exception of 
fungi and the true parasites, covering either the cell-walls or the 
spiral bands, as in Spirogyra, or the granular contents of the cells, 
which are composed of starch, or other similar bodies. If plants 
that have been grown in the light are placed in the dark, the 
leaves fall; and if others are produced, they have a whitish colour : 
again, if the plants that have been thus grown in the dark are 
removed to the light, the leaves soon lose their white hue, and 
eventually assume their natural colour; the rapidity with which 
they become green, and the intensity of their colour, will be in 
proportion to the amount of light to which they are exposed. The 
different rays of the spectrum have a varying influence in pro- 
moting the formation of chlorophyll, and some difference of opinion 
exists as to which rays are the most active in this respect, but the 
majority of experimenters agree that the yellow rays are those 
which are the most essential, because they have the greatest effect 
in promoting the decomposition of carbonic acid. 
EXPLANATION OF PLATE CLXXIX. 
Fic. 1.—Chlorophyl!1 normal. Fic. 7.—Petals of red Cineraria. 
», 2.—Chlorophyll acid. Hil 8! 
»» 3.—Leaves of Lobelia. » 9. ¢ Litmus. (Figs. in text.) 
» +4.—Petals of blue Cineraria. syn LOE 
», 0.—Leaves of Shumac. », 11.—Hypericene normal. 
» 6.—Tradescantia. 5, 12.—Hypericene acid: 
Note.—Class 1 isa symmetrical band. Class 2 is an unsymmetrical band. 
VOL, . XVII. g 
