ADAPTATION. 21 



varieties (those which turned yellow the first year of plant- 

 ing out) that they only become green with difficulty, or not 

 at all. These die the third year, and sometimes even in the 

 second (Vialla, Noah, Rupestris X Cordifolia, Rupestris X 

 Cinerea, etc.). 



Finally, certain varieties do not become yellow the first 

 year, but only the second; and in this case not at the 

 start of the vegetation, but later on at the end of May or 

 June. 



They also become greener much earlier and much more 

 completely (the best forms of V. Berlandieri and its hybrids 

 with V. Vinifera). 



In cases where the soil is slightly calcareous while the 

 sub-soil is strongly so, the same phenomena sometimes 

 occur, but they become retarded, especially in warm and dry 

 localities. During the first, and even the second year, 

 chlorosis may not be apparent as long as the roots are in the 

 slightly calcareous surface soil, but directly they permeate 

 to the sub-soil chlorosis starts, and the vine goes through 

 the same phenomena. 



Such are the variations of intensity which chlorosis may 

 present with the age of plantation and the nature of the 

 soil. We shall hereafter give the explanation of this 

 phenomenon. 



These characteristics are proper to this disease; and if 

 they are found on vines dying from phylloxera, pourridie, 

 etc., it is always in calcareous soils. Whether healthy or 

 unhealthy, they never become yellow in clay or siliceous soil. 

 This is a very definite fact which will enable us to indicate 

 the exact cause of chlorosis in vines. 



Sometimes, however, we observe in siliceous-clay soils, 

 especially when the spring is cold and rainy, vines with part of 

 their foliage yellow, leaves normally developed, showing yellow 

 patches in places, or sometimes completely decolourized, 

 and presenting a great analogy with those of variegated 

 plants. Leaves variegated in this way seem to develop 

 normally, and do not dry; the tissues, even the most yellow, 

 remain alive, and often become completely green again. This 

 phenomena is after all only a variegation, the cause of which 

 is not yet known. 



In, short, withering vines in any soil often have, when the 

 spring is very rainy, a pale-green colour, which manuring 

 and the return of fine weather dissipate. 



