Anthraquinone pigments in galium

Abstract

The occurrence of chemical as distinct from morphological varieties has been shown in the plant Eucalyptus Dives by Penfold and Morrison (1928). An example of definite chemical variation in animals is that of the Dalmatian hound, where the excretion of uric acid peculiar to this variety was shown by Onslow (1923) to behave genetically in the same way as a morphological character. More recently Scott-Moncrieff (1936) and Lawrence and Scott-Moncrieff (1935), who have extended the earlier investigations of Mrs. Onslow (1925) on the genetics of the occur­ rence of the anthocyanins, which give the colours of flowers and fruits, have shown that the study of chemical genetics can give a clue to pro­ cesses taking place in the organism. This work forms the foundations for the development of the branch of biology—Chemical Variation. While, for example, a certain terpene may characterize a species, in some cases a chemical substance may characterize a whole genus or group of genera. The last consideration concerns the present work. Anthocyanins and substances related to them have been found by Robinson and Robinson (1934) to be almost general in the plant kingdom. The knowledge of hydroxyanthraqui nones in plants, the substances with which the present paper is concerned, has recently received two important additions—the work of Raistrick, Robinson, and Todd (1934) on the Mould Helminthosporum and of Kögl and Deijs (1934) on the Toadstool Boletus. Previously, hydroxyanthraquinones were known in Lichens and in Angiosperms; in Rhammus and Ventilago (Rhammaceae), in Rumex and Polygonum ; in Cassia and Andira (Leguminosae); in Aloe (Liliaceae) as well as in Madder and several other members of the Rubiaceae. The anthraquinone structure occurs in isolated cases through­ out the plant kingdom, which suggests that, like the anthocyanidin and anthoxanthin structure, it may be the end product of a general type of metabolism leading to aromatic compounds.