On the Characteristic Colouring-matters of the Red Groups of Algae

H. C. Sorby
1875 Journal of the Linnean Society of London Botany  
IN my paper "On Comparative Vegetal Chromatology "* I shoaed that the three great divisions of Algae-the olive, the red, and the green-are, on the whole, very dehitely distinguished from one another by the presence or absence of the various green or yellow Rubstances insoluble in water belonging to the chlorophyl and xanthophyl groups. I now propose to consider more especially the general distribution of 8ome of the principal coloured constituents which are soluble in water. It would be
more » ... t t o End another series of colouring-matters of greater beauty, or with such remarkable and instructive chemical and physical pecu- liarities. Although all easily soluble in water, there seems very good evidence to prove that in the living plants they are either in a solid state or combined with a very small quantity of water, and not disseminated through the whole liquid contents of the cells, like the entirely different class of red colouring-matters found in the leaves of the higher classes of plants. On keeping the Alga? in a small quantity of water, they soon die and begin to decompose ; and then the various colouring-matters are set free and dissolved, the change being indicated by the absorption-band in the spectrum being a little nearer the blue end than in the spectrum of the living plant, and by the fluorescence being greatly increased. In some Alga? this change takes place very rapidly, and in some so slowly that the colouring-matters are lost by decomposition before a satisfactory solution can be procured ; but by using no more water than is necessary to cover the plant operated on in a small corked bottle, a solution may generally be obtained which is of beautiful pink or purple colour, according to the nature of the plant. Such a solution, after having been filtered, must be carefully studied by the same spectrum method as I have described in many previous papers, and by the employment of special means which I now propose to explain. The total number of different coloured substances charncteristic of the various divisions of the red groups of A l p is at least six. These are distributed in very variable proporiions in different *~'Pi-oc. Roy. Soc ~o l . sxi p 412,
doi:10.1111/j.1095-8339.1875.tb00214.x fatcat:mc3tas4xgjdohmuqw5nzyilmna