RESULTS OF EXPERIMENTS ON THE 

 FLORAL COLOURS. 



p. Q. KEEGAN, LL.D., 

 Patterdale, Westmorland. 



The experiments on the floral colours recorded in ' Nature,' 

 vol. LXI., pp. 105-6 have been continued and extended. It 

 was found that by mixing the aqueous solution of the pigment 

 with a small quantity of a solution of succinate of manganese, 

 and allowing the liquid to dry in a shallow basin, decisive 

 results were obtained. Thus it was observed that those pig- 

 ments, whose behaviour under the various processes hitherto 

 employed indicated a more or less complete deassimilation 

 {i.e.. tannic chromogen more or less fully converted to pigment), 

 now yielded reactions with precisely similar and comparable 

 indications. For instance, Cranesbill, Tufted Vetch, and Sweet 

 Pea dried up a deep pure blue, w^hile Poppy, Burnet, Cineraria 

 and Pcxonv dried up red, but Foxglove and Carnation showed 

 blue on the edges only, and Clover remained greenish. It was 

 natural that in course of time certain conjectures of a scientific 

 hypothesis should arise in the way of explaining the phenomena, 

 and the analyses of plants performed by myself (see ' The 

 Naturalist,' 1902-10) were extremely helpful in this respect ; 

 for thereby it was clearly shown that while the flowers of 

 certain plants were vividly and purely tinted, the quantity of 

 tannic chromogen in the same whole plant was remarkably 

 small ; in fact, in many cases the particular chromogen found 

 in any appreciable quantity was merely a tannoid capable of 

 yielding yellow pigments only. The conclusion irresistibly 

 pressed forward was, that the formation and development of 

 the blue and red pigments were strictly local and absolutely 

 confined to the floral envelopes, i.e., they were not necessarily 

 in any way dependent on the particular amount of tannin 

 produced by the plant organism in its entirety. 



This disclosure immediately threw upon the subject a vivid 

 light wherewith no one apparently had hitherto been irradiated. 

 True, it was previously known that the corolla was the seat of 

 active oxidation, that its colouration was the necessary con- 

 sequence of the development, and that its rapid growth was 

 effected in spite of a very reduced supply of nutriment, which 

 must inevitably bring about a notable impoverishment of the 



1910 June I. 



