[Letters to Editor]

Abstract

MR. COMBER'S suggestion (vol. ix. p. 484) that the coloured flowers of Fumaria attract insects to the uncoloured ones is very in-ingenious. Supposing that they are cross-fertilised, the case of Poinseltia is very pertinent, and is enforced by that of Dalechampia, also euphorbiaceous, in which the bracts, a beautiful rose colour before fertilisation, gradually assume afterwards the same green hue as the foliage when the bright colour is no longer needed. The chemical changes that take place in the flower at and after the period of its complete expansion must necessarily be complex, as well as varied in different cases. Rapid oxidation is probably one very effective agent in producing them, but the results will necessarily depend on what is operated upon. Hibiscus mutabilis is white in the morning, deep red by night. Species of Lantana, like Myosotis versicolor, pass through a whole series of colours as they expand. On the other hand all the beautiful species of Franciscea rapidly lose the tints with which their flowers open, and become nearly white. The final stages in the life of all the parts of the flower which are not accessory to the formation of the fruit are more or less processes of decay, and there is no absolute law that these should always be accompanied by inconspicuous or displeasing tints. The white flowers of Calanthe veratrifolia blacken when they are bruised; on the other hand, according to Kingsley, the crimson flowers of Couroupita guianensis turn blue when torn, as the pulp of the fruit is also known to do on exposure to the air. In the same way some fungi exhibit when bruised striking tints which yet can be of no service to them. Agaricus georginæ changes from snow-white to blood-red wherever it is touched, and the white flesh of Boletus cyanescens when broken changes instantly to the “most beautiful azure blue.”