Grape Grafting. 461 



ture is represented still more highly magnified. It is here seen 

 to be composed of three rows of cells running in a direction par- 

 allel to that of the bark. The number of these rows varies at 

 different times of the year, there being many more during the 

 period of active growth. 



Office of the cambium. — It will be noticed that the cambium 

 layer separates the wood from the bark. An interesting feature of 

 this layer is that after division the cells next the bark go to the for- 

 mation of bark, while those nearest the wood form woody fibre, yet 

 the origin of the two is the same. We may suppose the cells of the 

 central row to be divided into halves by a vertical wall. One half 

 will then go to the formation of either wood or of bark, as the case 

 may be, while the other half remaias to increase in size and to 

 divide as before. Thus the origin of both the young bark and of 

 the young wood is probably in a single row of cells situated be- 

 tween these two parts of the stem, and it is largely in this layer 

 that active growth in our common woody plants takes place. 



From the above it will at once appear that no union will take 

 place between stock and cion unless the living cells, or the cam- 

 bium layers of the two, are placed in close contact, and no graft- 

 ing can be successful where these conditions are not complied with. 

 Some plants appear to be more exacting in this respect than oth- 

 ers, and the grape, fortunately for the careless vineyardist, is not 

 so particular as are many of our cultivated trees and shrubs. It 

 will undure a certain amount of careless work and still eflfect a 

 union . 



This fact should not encourage poor or hasty workmanship. 

 All tendencies which lessen the chances of success deserve to be 

 studied so that they may be avoided. No sand or dirt should be 

 allowed to rest upon cut surfaces, if it can be helped, until after 

 the parts are placed in position. Such particles would prevent to 

 a greater or less degree the intimate contact of the two surfaces. 

 All cuts should ba made as smooth and as straight as possible so 

 that no projection of wood will prevent the two layers from press- 

 ing against each other. 



It is not essential to success that the cambium layer of the two 

 parts be in contact at every point. Such a result is almost im- 

 possible in practical work, and it is especially so in grapes where 



