CHAPTER yil 



EFFECT OF MANGANESE COMPOUNDS 



I. Presence of Manganese in Plants 



The presence of manganese as a constituent of plant tissues has been 

 kno'wn for many years, and in view of the close association between iron 

 and manganese it was natural that the early investigators should seek 

 for the latter element. De Saussure (1804) gives one of the earliest 

 references to manganese in plant ash, stating that it occurs in the seeds 

 ia less great proportion than in the stems, and also that the leaves of 

 trees contain less in autumn than in spring. At first oxides of iron and 

 manganese were put together as "metallic oxides" and little or no 

 attempt was made to separate them so as to get an idea of their relative 

 abundance. John (1814) gives a number of rough analyses of plants 

 and indicates the presence of manganese in many plants, including 

 Solarium tuberosum, Brassica oleracea viridis L., Conium^maculatum, 

 Aesculus (in outer bark), and Arundo Sacchar. No further references 

 presented themselves until 1847, as probably manganese was overlooked 

 and always classed with iron in any analyses made during that time. 

 Kane (1847) found traces of manganese in the ashes of some samples of 

 flax, but none in others, and examinations of the soils on which the 

 plants were grown gave similar results. Mayer and Brazier (1849) con- 

 firmed this result. Herapath (1849) analysed the ashes of various 

 culinary vegetables, finding manganese in cauliflowers, swede turnips, 

 beetroot, and in one variety of potato (Forty fold). 



Malaguti and Durocher (1858) tried to investigate the matter 

 quantitatively. The oxides of iron, manganese, and aluminium were all 

 classed together, and the mean percentage of the three varied from 

 •85 % — 5-06 % according to the varieties of plants concerned, Cruciferae 

 possessing least and Leguminosae most. Different mean results with 

 the same plant were obtained fi-om different soils. 



Wolff (1871) made other quantitative analyses including Trapa 



