ADAPTATION. 39 



does not become more yellow than when growing tmgrafted 

 on its own roots, but when grafted on Riparia, Solonis 

 Rupestris, etc., it becomes withered, distorted, and dies. In 

 the same way different stocks such as Riparia, Rupestris, 

 Solonis, Lenoir, etc., may remain almost green and develop 

 normally as long as they are growing on their own roots, 

 but when grafted they very quickly succumb. 



The weakening following grafting is not therefore the 

 result of the operation of grafting itself; it results only 

 from internal and external differences, or to be more exact 

 from vital differences existing between stock and scion, 

 or as it is called from the want of affinity between the varieties 

 or species grafted. The swelling often existing at the 

 knitting point has nothing to do with the weakening of 

 grafted vines, neither has the knitting itself. No doubt a 

 plant badly knitted, when placed in unsuitable conditions for 

 growth, will become yellow quicker than a well-knitted plant 

 (the chlorotic plants existing sometimes disseminated here 

 and there in very green vineyards, are almost always grafts 

 badly knitted); but the perfection of the knitting has not 

 the importance attributed to it, from the point of view of its 

 action on the change of colour of the leaves. 



An imperfect knitting may be compared to a wound on the 

 trunk of a vine ; it has equal, but not greater importance. 



We have shown that it is at the second year after planting 

 that vines are most chlorotic. It is just at that time 

 that grafting on the growing plant is performed. The 

 weak state resulting from the want of adaptation to the soil, 

 which is at its maximum then, is still increased by the 

 weakening effect of the grafting. Grafting on the growing 

 plant takes place therefore under more unsuitable conditions 

 from this point of view; that is to say when the stock seems 

 to suffer most from the presence of limestone. It is not a 

 very serious trouble in siliceous-clay soils, but in soils rich 

 in lime it is certainly so. We should therefore graft on the 

 growing stock when it suffers least from the operation, that 

 is to say, at the third or fourth year, when the plant has re- 

 gained its normal green colour. This method has been followed 

 in many vineyards of the south of France and the Charentes, 

 and everywhere the results have been most satisfactory. 



We may obtain the same result by grafting the cutting 

 before planting out. A well-knitted plant, well rooted pre- 

 viously in the nursery, may become yellow when planted out 



