ALBERT

Notes: Summary Graftings between alkaloid-producing and non-alkaloid plants of theSolanaceae family have indicated the importance of the root and other subterraneous plant organs for the formation of alkaloids. If, for example, black nightshade(Solanum nigrum) is grafted on tobacco(Nicotiana Tabacum), the otherwise non-nicotinous scions ofSolanum nigrum contain considerable quantities of nicotine. If on the other hand the black nightshade is used as stock and the tobacco as scion, the nicotine completely disappears from the graftings. Similar results have been obtained from experiments with tomatoes(Solanum Lycopersicum) on one hand and thorn-apples(Datura Stramonium) and deadly nightshades(Atropa Belladonna) on the other. Morphological and histochemical investigations have likewise drawn attention to the subterraneous plant organs as centres of alkaloid formation. In this way hordenine is formed and stored only in the roots ofHordeum murinum, and berberine is to be found almost exclusively in the roots ofMahonia Aquifolium. Graftings which are carried out withNicotiana Tabacum, which contains nicotine, and withNicotiana glauca, which contains anabasine, have demonstrated the pronounced reciprocal influence of the alkaloid metabolism of scion and stock. These results are, however, not so conclusive as those obtained from graftings of non-alkaloid and alkaloid-producing scions or stocks. Nevertheless the following conclusions can be drawn from these investigations: 1 The grafted plants form more alkaloids than the test plants. 2 In graftedNicotiana glauca anabasine formation strongly prevails. 3 The total replacement of the nicotine by anabasine in grafts ofNicotiana Tabacum onNicotiana glauca is not based on the migration of the anabasine from the stock in the scion; it is due to the complete modification in the alkaloid metabolism of the scion under the influence of the stock. A final decision whether the plants in question form the corresponding alkaloids or their precursors, or indeed both, in their subterraneous organs, can at present not yet be given. The investigation of these questions will also clarify in each individual case the migration of these alkaloids. Further experiments are here required, as it appears that the various plants react differently in this respect on being grafted. Perhaps it will be possible to throw light on this question by means of other methods.