Effect of Zinc Compounds 37 



Armeria vulgaris. 



Root 4-74 / ash, 0'17 % ZnO, 3-58 / ZnO in ash. 



Stem 5-37 / a 0'02/ 0'37 / 



Leaves 9*36% O'll / 1'17/. 



Flowers 6'08/ 0-07 /. 1-15 / 



Silene inftata. 



Root 2-71 % ash, 0-02 / ZnO, 074% ZnO in ash. 



Stem I 



Leaves V 11-43 / 0'22/ 1-92% 



Flowers' 



Freytag (1868) carried out various experiments on the influence of 

 zinc oxide and its compounds on vegetation, and found that all plants 

 are capable of absorbing zinc oxide by their roots when grown on soils 

 containing such oxide. Generally speaking the zinc is deposited chiefly 

 in the leaves and stems, very little being found in the seeds, such 

 minute traces occurring that he stated that the seeds must be harmless 

 for men and animals. The general content of ZnO in plants is given as 

 5 1'0/ f asn except in the abnormal case of plants growing on 

 calamine. 



Lechartier and Bellamy (1877) demonstrated the presence of zinc in 

 such food substances as wheat, American maize, barley and white haricots, 

 but they failed to find it in maize stems and beetroot, so they cautiously 

 concluded that if it does occur in the latter cases it must be far less in 

 quantity than in the former. Hattensaur (1891) analysed the ash of 

 Molinia ccerulea and discovered the presence of copper, manganese, 

 zinc and lead, zinc oxide forming '265 % f the total ash, (006 % f the 

 air dried plant). 



Jensch (1894) observed that the flora on calamine soils was some- 

 what scanty, the chief plants that came under his notice being Taraxa- 

 cum officinale, Gapsella Bursa-pastoris, Plantago lanceolata, Tussilago 

 Farfara, and Polygonum aviculare, all of which showed certain morpho- 

 logical peculiarities. Generally speaking the growth of these plants on 

 the calamine soils was weak and poor, the stems and leaves being very 

 brittle. Jensch found that the roots were deformed and showed a 

 tendency towards a plate-like superficial spread of root. The leaves of 

 Tussilago were uneven in shape and lacked the white hairs on the under 

 side, the flower stalks were twisted, while the flowers themselves were a 

 deep saturated yellow colour. The stems of Polygonum aviculare were 

 much thickened at the nodes, the leaves weak and rolled in character, 

 while the flowers were long-stalked, the calyces being usually of a 



