158 THE APPLE CULTURIST. 



climate, and for maintaining in even balance that degree of 

 warmth most favorable to the healthy exercise of their vital 

 functions ; and perhaps the fact is not sufficiently realized 

 how admirably suited this external covering is for such a 

 purpose. Wood, in the direction of across the grain, is a 

 non-conductor of heat in an eminent degree ; and the outer 

 layers of bark are even greatly more so. Hence we would 

 never advocate the practice of scraping the bodies of fruit- 

 trees simply to promote their fruitfulness. The practice 

 promotes no such end. When the bodies of trees are 

 scraped, the denuded parts should be protected with a coat 

 of pitch and tallow. (See p. 159 for a cut of a tree-scrap- 

 er.) The. chief reason urged in support of the practice is, 

 that it lightens the trees of a load of dead and useless mat- 

 ter which can not be of further benefit ; but, on the contra- 

 ry, when allowed to remain, it is only a harbor for insect 

 enemies, and for the growth of moss and lichens. It is 

 doubtless true that the depredations of insects have been 

 lessened by the process. But as for lichens, we are at a 

 loss to understand how they can be hurtful to trees; for, 

 although growing upon them, they live exclusively upon 

 food drawn from the atmosphere. It is not claimed that 

 trees derive any benefit from those epiphytes, unless in bleak 

 and exposed situations they supplement the bark in afford- 

 ing protection. But when found in excess upon apple or 

 pear trees of immature age, they may be accepted as a sign 

 that, from some cause or other, those trees are not in such 

 satisfactory condition as could be desired. Want of thrift- 

 mess in trees favors the growth of lichens ; and this may be 

 induced by a variety of causes, either singly or in combina- 

 tion, such as impoverishment of the soil, want of drainage, 

 or exposure to the rigors of a severe and variable climate. 



The long strips of dead bark hanging from the bodies of 

 large hickory-trees are of more service than injury. In no 



