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 XXII. Intelligence and Miscellaneous Articles, 



ON THE OCCURRENCE OF ZINC IN THE VEGETABLE ORGANISM. 

 BY A. BRAUN. 



IT is well known that the calamine hills of Rhenish Prussia and 

 the neighbouring parts of Belgium possess a peculiar flora ; visi- 

 tors to these regions are particularly surprised by a species of violet 

 allied to Viola tricolor, which unfolds its beautiful yellow flowers in 

 uninterrupted profusion from spring until the end of autumn, and is 

 known in the neighbourhood of Aix as the Calamine violet, or in 

 the dialect of the district " Kelmesveilchen." This plant has been 

 described by Lejeune in his " Revue de la Flore de Spaa " as a 

 distinct species under the name of Viola calaminaria, but he has 

 since characterized it (Comp. Fierce Belgica) as Viola lutea. Smith. 

 Koch and other authors have also rightly considered it as a variety 

 of V. lutea, Smith {grandiflora, Huds.), a species principally distin- 

 guished from V. tricolor by its filiform subterraneous i-unners, by 

 means of which it survives the winter. In its habits it is remarkably 

 distinct from the ordinary Viola lutea of the Alps, as well as from 

 the form of this plant occurring on the higher Vosges on granitic 

 and syenitic soils (described by Spach as Viola elegans) ; its stem 

 being more procumbent and repeatedly branched at the base, and 

 the flowers being generally smaller. I will not, however, express 

 any further opinion as to whether this violet may or may not be a 

 distinct species, for the violets of the same group as V. tricolor pre- 

 sent so many diflficulties to systematic botanists in consequence of 

 their extraordinary variability, that it is diflScult to find the middle 

 course between the union of them all under one name, and the 

 establishment of a multitude of species. Many other plants grow 

 in company with the Viola calaminaria, which, although in this 

 district peculiar to the calamine hills, nevertheless grow in other 

 localities in soil free from calamine. 



The colour of the flowers of the Viola lutea of the Alps and 

 Vosges varies from the darkest violet to the purest yellow, whilst 

 the flowers of V. calaminaria, at least in the neighbourhood of Aix, 

 are almost always yellow. On the borders of the calamine district 

 specimens are met with here and there with pale violet, or bluish, or 

 mixed blue and yellow flowers, which have been regarded by Kalten- 

 bach as hybrids between this plant and the V. tricolor, which cer- 

 tainly occur on cultivated land in the neighbourhood. But I have 

 also seen a specimen of the true V, calaminaria from the calamine 

 region of Westphalia which is of a dark violet colour. The plant 

 when cultivated in gardens is said to change and become like the 

 common V. tricolor. 



The connexion between the occurrence of the V. calaminaria and 

 the presence of calamine in the soil, which is so constant that even 

 mining experiments have been undertaken with good results from 

 the indications furnished by this plant, induced me, when in Aix, to 

 urge M. Victor Monheim of that place, to examine the plant 

 especially with reference to its containing zinc. He afterwards 



