PBUIOTG GKAPE VINES. 131 



extremities of the old branches do not exceed from 

 five to eight. 



Upon these principles is founded the rule which 

 directs us to cut back plants which have made a 

 weak growth, or have become old, gnarled and hard, 

 so that they may throw up strong, vigorous shoots. 



III. The sap supplied by the roots must be elabo- 

 rated by the leaves, before it is fitted for the forma- 

 tion of wood or fruit, and the development of the 

 roots is in direct proportion to the increase of leaves. 



From this, it follows : 1st. That it is injurious to 

 remove the leaves from the plant, with a view to 

 ripen the fruit by the admission of sun and air (this 

 point has been fully discussed, page 110, et seq). 



2. That during the first two years' growth of the 

 plants, the production of leaves should be encouraged 

 as much as possible, so as to aid in the development 

 of roots. Hence the plants should be carefully tied 

 up, so as to preserve the leaves clean, active and unin- 

 jured, and abundant light and air should be furnished, 

 so that they may be able to perform their part with 

 efficiency. This being the case, it may be asked why 

 we advise the stopping of the laterals which certainly 

 form leaves, and hence must increase the growth of 

 the roots. Two reasons may be given for the practice 

 either of which are ample. The first is that it is not 

 the leaves, per se, which do good, but their action on 



