350 PROF. H. M. WAED AND MISS E. DALE ON CEATEROSTIGMA PUMILUM. 



For the sake of comparison we have examined microchemically the colouring-matters 

 in various plants in which they are present in a solid form and which have not been 

 mentioned by Courchet. Some of these give the reactions which, according to 

 Zimmermann ('Botanical Microtechnique,' translated by Humphrey, 1893, p. 101), are 

 characteristic of carotin, and which also agree with those of Courchet's xanthic series. 

 Carotin, the name originally given to the yellow colouring-matter first obtained from the 

 roots of the cultivated carrot, is now proved to be more widely distributed, and to occur 

 not only in many plants but in some animals [cf. Zopf, " Zur Kenntniss der Parbungs- 

 ursachen niederer Organismen," Beitriige zur Physiologic und Morphologie, 1892 and 

 1893). It is supposed by some authors to be identical with that which has received the 

 following names, as well as many others — chlorophyll-yellow, xanthophyll, erythrophyll, 

 chrysophyll, etc., and to which is due the colour of leaves in autumn. The characteristic 

 reactions of carotin with iodine and with concentrated sulphuric acid are those which 

 distinguish the xanthic series as a whole. With regard to its behaviour towards alcohol, 

 ether, benzine, and carbon bisulphide it in some respects resembles the yellow pigments, 

 and in others the orange-yellow and orange-red colours which form the two divisions of 

 Courchet's xanthic series. 



By way of control experiments, we have compared the various reactions of the 

 colouring-matter in the root of Craterostigma with those of the carotin in the flowers of 

 Tropceolum majus, Linn. 



Among other plants of which we have examined the colouring-matter for the sake of 

 comparison was Chamcedorea SartoiHi^ Liebm., which has thick floral axes coloured bright 

 orange-red. The colouring-matter occurs as red granules in certain of the plastids 

 which have also a coloured stroma. It is chiefly confined to a broad band of cells near 

 the periphery, while those lying more internally contain chloroplasts. The cells in the 

 centre of the axis are colourless. 



In many of its reactions the colour in CMmcudorea resembles carotin, but in some it 

 is like the colour in the roots of our plant. Though many of the reactions of the latter 

 are peculiar, yet on the whole they show a marked resemblance to those of the colouring- 

 matter in the flowers of Aloe. For the sake of comparison with Courchet's results for 

 Aloe and with our own for Craterostigma, we have examined microchemically the 

 colour-bodies in Gasteria, a genus closely alied to Aloe. The results of a comparison of 

 the solid colouring-matters contained in the flowers of TropcBoliim majus, the floral axis 

 of Chamiudorea Sartorii, and in the flowers of Gasteria formosa, Haw., with that in the 

 root of Craterostigma pumilum are summarized in the accompanying Table (p. 352) and 

 may now be discussed. 



The reactions of the red colour of the roots of Craterostigma with iodine and with 

 concentrated sulphuric acid separate it at once not only from carotin, but from the whole 

 xanthic series. With iodine the colour is not dissolved, but turns dark brown. With 

 concentrated sulphuric acid the colour also at first becomes brown and then dissolves, 

 forming a yellowish-brown fluid, but leaving an insoluble residue consisting of colourless 

 granules. 



Perhaps the most curious reaction, and one which suggests those of the cyanic series, 



