34 Meyen's Report for 1839 on Physiological Botany. 



(lxv. p. 165 — 175), he had already proved the identity of the 

 red colouring matter in the flowers of the Iridece, Labiata, 

 Rosacea, Ranunculacece, Geraniaceee, Cannacece, Malvaceae, 

 Leguminosm, Papaveracem, Myrtaceae, &c. ; and that the red 

 colour in the bracts of Melampyrum arvense, in the leaves of 

 Caladium bicolor, in the fruit oiPrunus cerasus, Ribes rubrum, 

 Sorbus ancuparia, is similar, and that the identity extends to 

 the red matter which colours the leaves in autumn. 



From M. Morren* we have received anatomico-physiological 

 researches on the appearance of indigo in Polygonum tincto- 

 rium ; the work had been read to the Brussels Academy be- 

 fore the appearance of a similar one by M. Turpin, which was 

 mentioned in the former Report, and is therefore to be con- 

 sidered as cotemporary with it. The views of MM. Turpin 

 and Morren on the production of the indigo differ from each 

 other. The former found this substance in the sap-globules 

 of the cells which were coloured green by chlorophyll, but 

 M. Morren believes that the indigo is produced in the inter- 

 cellular sap (by which is meant the ordinary cell-sap). I may 

 here state with certainty, from my own observations, that the 

 blue colouring matter in Polygonum tmctorium is formed out 

 of the previously green-coloured cell-sap globules. Whether 

 however, in the colourless cell-sap of that plant, a substance is 

 contained in solution which changes into indigo (as appears 

 from M. Morren's statements) I cannot say, having made no 

 decisive observations, and this is not at present the time for it. 



The expressed sap of the leaves ought to be perfectly fil- 

 tered and then treated for the formation of indigo, by which 

 the question would be settled. Indigo is formed in all parts of 

 Polygonum, but principally in the leaves ; here it is found in 

 the parenchym and also in the nerves, and only the " tissu 

 fibro-vasculaire" does not contain a trace. 



M. Morren directs attention to the regular position of the 

 adventitious roots in this plant, which, as is so often the case 

 with the genus Polygonum, grow out of the nodes. 



M.Hunefeldfhas communicated some more of his continued 

 researches on vegetable colours ; he has also found that there 

 is not the same similarity between the colours of the different 

 parts of plants, as for instance, the roots, leaves, flowers, and 

 fruits, as would seem from outward appearances, and as some 

 botanists have asserted. Very few changes of colour in plants 

 are produced by the action of acid or basic substances. More- 

 over M. Hunefeld has published a long series of experiments 



* Mem. de PAcad. Royale des Sc, &c, de Bruxelles, tome xii. 

 f Beitrage zur Chemie der Pflanzenfarben. — Erdmann & Marchand's 

 Journal fur prakt. Chemie, 1839, 1 Bd. p. 65—80. 



