Jensch (1894) observed that the flora on calamine soils was somewhat scanty, the chief plants that came under his notice being _Taraxacum officinale_, _Capsella Bursa-pastoris_, _Plantago lanceolata_, _Tussilago Farfara_, and _Polygonum aviculare_, all of which showed certain morphological 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 purple red colour. The following figures are given for the quantities of zinc carbonate (ZnCO₃) in the ash of these two plants:-- _Tussilago Farfara._ Root Leaf-stalk Leaf-blade 2·51%–3·26% 1·75%–1·63% 2·90%–2·83% ZnCO₃ = 1·629%–2·115% 1·136%–1·058% 1·882%–1·836% ZnO. _Polygonum aviculare._ Root Stem Leaves 1·77%–1·93% 2·25%–2·86% 1·24%–1·49% ZnCO₃ = 1·148%–1·252% 1·46%–1·856% ·804%–·967% ZnO. Other analyses of plants from zinc soils as against controls from normal soils indicated the high water and high ash content of the zinc plants, though the dry matter was low, and it is suggested that the increase of the ash may be connected with a stimulation caused by the zinc salts, unless it is due to phosphoric-acid hunger, since the calamine soils concerned are very deficient in phosphorus. Javillier (1908 c) corroborated the early statements of Risse as to the presence of considerable quantities of zinc in certain species of _Viola_, _Thlaspi_ and _Armeria_, and also he cited a list of other plants in which zinc occurs in some quantity. Javillier, however, is of opinion that zinc oxide, like the oxides of iron and manganese, is very common in plant ash, being present in all plant organs. Zinc is specially abundant in Coniferae, where it is probably characteristic, as is the presence of manganese in the ash and manno-cellulose in the wood. The so-called “calamine” plants show great powers of accommodation to large amounts of zinc. Klopsch (1908) analysed 17 species of plants grown on soil in the vicinity of zinc works, and showed that the plants evidently absorb small quantities of zinc from their surroundings. He also regarded zinc as a normal constituent of certain plants. II. EFFECT OF ZINC ON THE GROWTH OF HIGHER PLANTS. 1. _Toxic effect._ (_a_) _Toxic action of zinc salts alone in water cultures._