«}2 KEKGAN : CHEMISTRY OF THE ROSACEA. 



dye-stuffs — the aniline dyes especially. Now, among the derivatives 

 of benzene which are found contained in the petals, etc., of red and 

 blue flowers, the most frequent, and often the only ones, are tannin 

 and rutin, and there is satisfactory evidence that the production of 

 the floral pigments is due entirely or mainly to these two bodies. 

 The substance which tinges the yellow, orange, and brick-red flowers, 



r 



fruits, and pollens is carotin, which, it has been conjectured, is 

 a derivative of anthracene — a hydrocarbon which furnishes the basis 

 of some of the most brilliant dye-stuffs of our manufacturers. Thus 

 far only, therefore, merely in this generally related way can 

 a connection be traced between the natural colouration of flowers 

 and the artificial colouration derived from coal-tar. However, in 

 any case, is it not interesting to examine chemically the beautifully 

 painted petal, leaf, or fruit, in order to observe whether tannin or 

 rutin can be detected therein, and if so, then to proceed further with 

 the inquiry and endeavour to discover in what way these almost 

 ■colourless bodies are transformed in the living plants so as to become 

 actual colouring matters ? This last topic cannot, however, be 

 discussed just at present, so let us, by the light of the explanations 

 afforded in the foregoing lines, render a brief summary of the results 

 of the chemical investigation which has been described in the 

 January number of this journal. 



Summary. — It was <ccn that no tannin was found in the flowers 

 of the Hawthorn, Mountain Ash, or Wild Cherry, hence they are 

 colourless ; the rutin which is present in all three not yielding by 

 itself a colouring matter, though doubtless in cases where it coexists 

 with the tannins, it helps these in their tinctorial properties. In the 

 flowers of roses a comparative abundance of tannin and rutin was 

 detected, which are evidently liberally distributed thereto by the 

 ives, for in the bark, pith, and medullary rays of these plants 

 particular series and layers of conducting cells exist, which are 

 richly charged with tannin, etc. ; in Wild Rose petals the tints are 

 comparatively feeble, but in garden Roses, whose petals being les 

 vegetative are therefore more readily the seat of katabolism or strong 

 metabolism, the colouration is developed to the full. The cases 

 of the Blackberry and the Meadow Sweet seem to stand on quite 

 a different footing, for here we have petals rich in tannin and yet 

 devoid of colour. How may this anomaly be explained? Simply 

 in this way, that the pigment is not forthcoming by reason of the 

 coexistence of powerful reducing agencies, e.g., the aldehyde in the 

 Meadow Sweet (contra Spine a callosa, which is red, is odourless), and 

 some strong acid or saccharine matter in the. Rlnckherrv • mmwwer. 



peci 



N.tUT i*t, 



