Chap. V] THE SOIL 95 



are, on the contrary, certainly produced by the decomposition of the 

 bicarbonate and the precipitation of the insoluble neutral salt, resulting 

 from assimilation '. 



Calcium carbonate is present in all soils and in all waters, and in small 

 [uantities is endured by all plants. No appreciable action on physiological 

 processes occurs in such cases. On the other hand, a nutritive solution 

 '■ich ill calcium is poisonous to many plants, whilst by others it is tolerated in 

 afferent cases to a greater or less extent. Those plants that tolerate larger 

 .juantities of calcium carbonate have their metabolism likewise affected 

 by it, and consequently often undergo visible structural modifications, 

 "alciuni carbonate thus acts as do sodium chloride, serpentine, and 

 :alamine. 



The poisonous action of calcium carbonate on manj- plants is most easily 

 )roved in the case of aquatic vegetation. A supply of water rich in calcium, 

 or instance, suffices, as Sendtner proved, in a short time to kill the species 

 )f Sphagnum and is not less poisonous to other aquatic mosses. The 

 iame holds true for many Algae that are otherwise common, if we may 

 udge by their constant absence from water that is rich in calcium. Many 

 errestrial plants are scarcely less susceptible. Thus, according to Christ, 

 I mere sprinkling with water rich in lime sufliccs, in a short time, to kill 

 3rosera and most of the other plants associated with bog-mosses on peat- 

 )0gs. According to the same investigator, Lomaria Spicant, AUosorus 

 rispus, Saxifraga aspera, Phyteuma hemisphaericum, Androsace carnea, 

 nd many others behave in a similar way. On a substratum rich in lime 

 •ierner cultivated various plants that never appear on a calcareous soil : 

 they at once sickened and died without blossoming.' Among trees, the 

 weet-chestnut and Pinus Pinaster cannot tolerate a calcareous soil ; accord- 

 ng to Chatin, even three per cent, of calcium in the soil is fatal to the 

 weet-chestnut. 



Plants that tolerate large quantities of calcium owe this capacity, as in 

 he case of halophytes in relation to sodium chloride, to a power of 

 ccommodation which is often associated with visible structural modi- 

 cations. The connexion between these variations and the influence of 

 alcium can be explained just as little, either physiologically or oeco- 

 Dgically, as the variations induced in Algae by solutions of common salt, 

 r as the production of peculiar varieties of plants on calamine and serpentine 

 Dils. Possibly we may also include under the same category of chemical 

 ifluences certain modifications induced by parasitic fungi in Euphorbia, 

 anemone, and other plants. 



The first experimental investigations into the influence of lime on the 

 ructure of plants were carried out by Bonnier, after he had noticed that 

 )nonis Natrix, on soils poor in calcium, possesses a physiognomy different 



' Pringsheim, op. cit. 



