670 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Spectra of the Pigments of Green Leaves and their Derivatives.* 

 — Herr E. Wegscheider gives particulars, in the form of comparative 

 tables, of the position of the bands and the maximum of absorption in 

 the cases of the spectra of (1) the living leaf; (2) tincture of chloro- 

 phyll; (3) alcoholic solution of the crystallized chlorophyllan 

 obtained by Tschirch ; (4) the pure chlorophyll of Tschirch ; (5) the 

 alkali-chlorophyll of Tschirch ; (6) the y-xanthophyll of Tschirch in 

 etherial solution. 



' " Red Pigment in Flowering Plants.f — Dr. J. Wortmann replies 

 to the statements on this subject by Dr. H. Pick, many of which he 

 considers to rest on erroneous observation. Especially he objects to 

 Pick's view on the influence of the red pigment in the transport 

 of starch, in which he neglects the fact of the difference in the ob- 

 jective intensity of rays of the same wave-length which have passed 

 through media of different colours. 



Identity of the Orange-red Colouring Matter of Leaves with 

 Carotine.t — M. Arnaud has prepared from the leaves of the spinach 

 the orange-red colouring matter called by Bougarel erythrophyll. 

 After purifying by repeated distillations in benzine it appears in 

 small flattened rhombic crystals, dichroic, and with the iridescence of 

 certain anilin colours. He finds this substance to be identical in its 

 crystalline form, its solubility, its fusing point (168° C.) and in other 

 characters, with carotine, the red colouring matter of the carrot, to 

 which Husemann gives the formula Ci8H240. The same substance 

 occurs also in the leaves of the mulberry, the peach, the sycamore, 

 and the ivy, and in the fruit of the gourd. 



Formation of Starch in the Leaves of the Vine.§ — ^In pursuance 

 of the experiments of Prof. Sachs || on the formation of starch in 

 leaves, Sig. G. Ouboni has made a series of observations on its presence 

 in the leaves of the vine. In March and April, when the leaves are 

 first formed, starch was never found, even in bright sunshine. It 

 first made its appearance in May, and the quantity increased con- 

 tinually till July. This is not solely dependent on difference in 

 temperature, since starch is still formed in the leaves at the end of 

 October and in November ; while even in the height of summer the 

 young leaves and shoots are not able to form starch until they are at 

 least a month old. It depends, however, to a certain extent on the 

 maturity of the chlorophyll-grains. In a leaf containing no starch at 

 the outset, abundance was found after an hour's exposure to the direct 

 action of the sunlight; and the maximum quantity was obtained by 

 two hours' intense sunshine. Four hours of complete darkness is 

 sufficient to cause the whole of the starch to become absorbed. 



Although tlie youngest leaves are unable to form starch, the 



* Ber. Deutsch. Bot. Gesell., ii. (1885) pp. 494-502. 

 t Bot. Ztg., xliii. (1885) pp. 39-43. See this Journal, iv. (1884) p. 257. 

 X Comptes Eendus, c. (1885) pp. 751-3 



§ Kivista di Viticoltura ed Enologia Italiana, ix. (1885) p. 13. See >latur- 

 forscher, xviii. (1885) p. 224. 



11 See this Jourual, iv. (1884) p. 589. 



