298 RECORD OF CURRENT RESEARCHES RELATING TO 



Formation of Chlorophyll in the Dark. * — M. Flaliault has re- 

 investigated all those cases where chlorophyll has been found in organs 

 completely excluded from the influence of light, viz. (1) the embryo 

 of Pinus and other conifers which become green at the moment of 

 germination ; (2) the embryo of many phanerogamous plants protected 

 by a thick, opaque integument, as Euonymus, Acer, Haphanus, Astra- 

 galas, Celtis, Tropceolum, Pistacia, Viscum, Citrus, Geranium, and 

 Cephalaria ; and (3) the fronds of some ferns. He first satisfied 

 himself that the green colouring matter was in these cases identical ; 

 at all events, that it had the power of decomposing carbonic acid. In 

 certain cases M. Flahault came to the conclusion that this chloro- 

 phyll was formed in the light, as in the case of some embryos whose 

 integuments are in an early stage thin and transparent ; the chloro- 

 phyll having in these cases the power of continuing its existence 

 after the exclusion of light. In other cases, however, there can be 

 no doubt that it is formed in absolute darkness, and that it is under 

 these circumstances jiroduced at the expense of the nutritive materials 

 stored up in the plant. 



Colouring Matter of Flowers.f — After reviewing the conclusions 

 of previous writers on this subject, M. Flahault records the results of 

 his own experiments on the origin of the various colouring matters in 

 the petals of flowers. 



A solid insoluble pigment, the xanthine of Fremy and Cloez, is in 

 the first place to be distinguished from all the soluble colouring 

 matters, blue, yellow, red, and their mixtures, all of which are acted 

 on very readily by reagents, and which are usually found only in the 

 epidermal cells. 



If a crocus is examined some weeks before the expansion of the 

 leaves and flowers, the perianth is found to be almost completely de- 

 veloj)ed, but still colourless, while the stamens and stigmas have 

 already assumed their bright colour. At the same period the Jonquil, 

 Narcissus odorus, Fritillaria Meleagris, &c., have not developed a 

 notable quantity of any colouring matter, while the separate parts 

 are otherwise fully formed ; the moment the perianth expands, it at 

 once acquires its bright colour. In some varieties this is even the 

 case when the flower expands in the dark, although the leaves are 

 completely etiolated. The j)etals of some flowers, as for example 

 Anemone fulgens and Gentiana acauh's, contain a smaller or larger 

 amount of chlorophyll, which assimilates in the ordinary way. The 

 conclusion arrived at is that the development of the soluble colouring 

 matter of flowers is directly dejiendent on the nutritive substances 

 stored up in them, or on assimilation by chlorophyll. It may there- 

 fore be produced independently of light. 



The insoluble yellow pigment xanthine occurs in the petals of a 

 large number of flowers belonging to many different natural orders, 

 as in Banunculus, Primula, Cheiranthus, Galeohdulon luteum, Doronicum 

 platdagineum, Alyssum saxatile, Cypripedimn Calceolus, Azalea chinensis, 

 Uvularia grandijiora, Eranthis hyemalis, Forsytlda viridissima, Tussi- 



* ' Bull. Soc. Bot. Fraucc,' xxvi. (1870) p. 249. f I'ji^l', I'- 2G8. 



