THE FRENCH SYSTEM OF PETJNING. 279 



is admissible, the fillings performed by dentists, and 

 with the same object, to check the progress of decay.-^ 



" Season for Pruning. — The most favourable season 

 of the year for pruning is the autumn, when the days 

 are still long and pleasant. The sudden and severe 

 frosts, however, which often occur at this season of 

 the year, are dangerous, and in some instances have 

 a tendency to cause decay in freshly-made wounds. 

 In winter the days are too short, and often too stormy, 

 to allow continuous work of this nature ; while the 

 loss of sap which occurs when trees are pruned in 

 the spring, although considerably checked by the use 

 of coal-tar, is probably rightly considered injurious. 

 The leaves interfere with pruning during the summer 

 months, when, too, there is a danger of the workmen 

 inflicting injury on the growing tender shoots of 

 neighbouring trees ; but a tree may be pruned at any 

 season of the year, and the best time for pruning that 

 which is most convenient, and when it can be most 

 cheaply performed. 



"All trees, whatever the nature of the soil in which 

 they grow, may be advantageously and profitably 

 pruned, with the exception, perhaps, of trees growing 

 on very poor and barren soU. These, as a general 

 rule, can produce nothing more valuable than fuel, 

 and hardly justify the cost and labour of pruning. 



" Ttve use of Coal-tar. — Coal-tar, a waste product 

 of gasworks, is a dark-brown imperishable substance, 

 with the odour of creosote. It can be applied with 



^ If the wound or decay is there unprovoked and uninvited, cer- 

 tainly all should be done that can be done to check its progress ; but 

 no one would be Justified in creating such wounds by cutting off large 

 boughs if he could help it. 



