ADAPTATION. 15 



II. INFLUENCE OF THE SOIL. 



A. SOILS SLIGHTLY OR NON-CALCAREOUS. 



(a) Role of sand and day. In the case of clay- 

 siliceous or siliceous-clay ground, we have only to take into 

 account its compactness, degree of humidity, and fertility. 

 Besides that, what role should be attributed to the sand and 

 clay? Other things being equal, is it better for the sand to 

 be in greater proportion than the clay, or vice versa"? We do 

 not know. But it does not appear that this point is of much 

 importance. Chemically, these two elements have not much 

 difference in their action on the growth of the vine. Their 

 role is rather physical. They modify the nature of the soil, 

 and, according as one or the other predominates, the ground 

 is more or less humid, or more or less compact. 



Siliceous sands formed of fine particles, mixed with a 

 smaller quantity than 2 per cent, of cement, constitute light 

 soils. European vines grow well in them, and, without 

 attaining great dimensions, have a normal development. 

 It is not so with American vines Some of them, such as 

 Lenoir, Herbemont, Vialla, Rupestris du Lot, etc., have a 

 satisfactory growth. The Riparia and a few others do not 

 suit these soils, and are anything but vigorous when planted 

 in them. , 



(b) Compactness (Stiffness). The compactness of the 

 soil is due to an excess of clay, or an excess of very fine 

 siliceous sand. In the latter case, when the amount of clay 

 is less than 5 or 6 per cent., the soils are excessively hard 

 and compact after a drought, the roots penetrate them with 

 difficulty, and the vines do not grow well. An excess of clay 

 seems to be less objectionable. 



The compactness of the soil has a manifest influence. It 

 is an obstacle to a good growth of the vine, which, like all 

 plants, requires a friable, light, and warm soil. The more 

 these conditions are satisfied the more vigorous its growth. 

 It grows, however, in compact soils, but its vigour is less, 

 and likely its life also. American vines are affected in a 

 similar manner to European varieties, but some of them are 

 not suited by soils of this nature. These ar Riparia, most 



