Chap. V] THE SOIL 99 



in relation to tliis tlic smaller amount of chlorophyll that is present in the 

 lea\'es on the calcareous soil, we may with probability conclude that in 

 calciphobous plants, when they grow on calcareous soil, the absorption of 

 iron or its transport through the plant is prejudiced, and thus the formation 

 of chlorophyll is checked. Contcjean has also observed that the colouring 

 of Sarothamnus, Ulex, Calluna, Anthoxanthum Puellii is always yellowish 

 when they grow under such conditions. 



The physiological causes of the injurious influence of calcium carbonate on 

 certain species of plants are rendered more comprehensible by the researches 

 of Fliche and Grandeau ; but, on the other hand, the difference in the be- 

 haviour of different species remains quite unexplained. An affinity on the 

 part of calciphilous plants for carbonate of lime, similar to that of lialo- 

 phytes for sodium chloride and of nitrophytes for saltpetre, does not appear 

 be here in question ; the quantities of lime absorbed from the same soil 

 3y the different species of plants are indeed as a rule very unequal, but 

 .vithout any perceptible connexion with a greater or less capability the 

 slants may possess of thriving on a substratum that is rich in lime. 



In the planted forest of Champfetu, on soil poor in lime (0-357^ CaO), 

 here are found growing together the calciphilous Cytisus Laburnum 

 vith ::7-i5 °f CaO in its ash, the calciphobous Ulex europaeus with 

 ■5'97 °L CaO, the calciphobous Sarothamnus scoparius with 2,5-03 °/^ CaO, 

 nd the indifferent Robinia Pseud-acacia with 58-97 °/^ CaO. If we 

 onsider that the laburnum contains only half the quantity of ash contained 

 ly the other species it follows that although it is calciphilous it is poorer 

 n lime than its calciphobous allies. 



ii. CHARACTER OF THE FLORA ON CALCAREOUS SOIL. 



The flora of a district the superficial soil of which results, in some parts, 

 rem rocks poor in lime, such as granite, sandstone or slate, and, in other 

 •arts, from rocks rich in lime, exhibits, in the flora of the two kinds of soil, 



contrast that at once strikes the eye, although many plants occupy 

 oth the soil rich in lime as well as that poor in lime. Of plants in 

 -entral Europe strictly confined to a soil poor in lime are, for instance, 

 "alluna vulgaris, Vaccinium Myrtillus, Sarothamnus scoparius, Scleranthus 

 erennis, Rumex Acetosella. Digitalis purpurea : similarly, of species found 

 nly on calcareous soil there are Prunus Mahaleb, Aster Amellus, Hippo- 

 repis comosa, Teucrium montanum, T. botrys, Globularia vulgaris, Epi- 

 actis rubiginosa. Many species show merely a decided preference for 

 le one or the other kind of soil, without confining themselves to it so 



nctly. Thus the common bracken is rare!)- seen on calcareous soil, 

 ".nthyllis Vulncraria and Scilla bifolia rarely on soil poor in lime — a soil 

 eing considered poor in lime that contains less than 3 "f^. 



Owing to the injurious influence of carbonate of lime on certain species 



H 2 



