Manures and Chemical Applications. 229 



them. It is under the influence of heat, and especially 

 of a bright light, that this elaboration takes place. 



If the tree, or shrub, possesses great vigor, from 

 whatever cause that may arise, the sappy fluids will 

 reach the cellular tissues of the fruit in such abundance 

 that there will be no possibility of their being thoroughly 

 prepared. The watery exhalation which takes place at 

 the surface of the fruit, during its development, will be 

 insufficient to rid it of its superabundant juice. The 

 sugary and aromatic principles will be comparatively 

 scanty, and the fruit of inferior quality. These facts 

 are indisputable ; they occur every day, under the eyes 

 of agriculturists. The fruits of an old tree are all 

 other things being equal much more luscious than those 

 of a young tree growing vigorously. The fruit of a 

 pear-tree, grafted on a free stock, is inferior to that 

 nourished by the roots of the quince-tree. 



Heat and light, as we have already said, play an im- 

 portant part in this question, by affecting the watery 

 evaporation and the elaboration of the sappy juices 

 flowing into the fruit. It is for this reason, that fruits 

 gathered from trees trained against walls with a southern 

 exposure, are better than those developed in a northern 

 one. The grapes ripened under the climate of Paris 

 are less sweet than those of the same descriptions grown 

 under the southern sky. 



Another consequence of excessive vigor, is the delay 

 in the ripening of the fruits. For, the chemical reac- 

 tions which take place in the tissues of fruits, and which 

 influence their ripening, begin to take effect only from 

 the moment the vegetation of the tree is nearly at a 

 stand-still that is to say, at that period when the sappy 



