BIRCH 135 



flat, membranous wing surrounding them. This wing 

 is Nature's provision for their dispersal, the broad plate- 

 like form being admirably adapted for this. These little 

 fruits are produced in great profusion and form a very 

 welcome food, and especially in high latitudes, to many 

 species of birds, such as the black grouse and ptarmigan. 

 The siskin is particularly partial to them, and may be seen 

 diligently investigating the catkins in search of them. 



The sweetness of the sap that exudes so freely from the 

 birch renders it very attractive to various kinds of insect 

 life, and a knowledge of this fact is of great value to the 

 entomologist, who is careful to keep an eye upon any of 

 these trees that he may find. The sap undergoes some little 

 fermentation, and butterflies, wasps, and other insects succumb 

 to the temptation. Inebriation is the result, and those that 

 take part in this debauch become often so hopelessly 

 incapable that they can be easily picked off by the hand 

 from the stems or from the surrounding rocks or herbage. 

 Peacock butterflies and red admirals are generally the 

 most numerous. The very rare Camberwell beauty is 

 also one of the species that yield to this temptation and 

 fall, willing victims, into a state of shocking intemperance. 



Economically the birch is of much value, and especially 

 in those sterile lands where it flourishes so well and where 

 so much else is wanting. Its timber supplies fencing, 

 flooring, barrels, and many other useful things ; its bark 

 is moulded into the canoe, or forms the shingles of the hut, 

 its larger branches yield welcome fuel, and its smaller ones, 

 twisted together, serve as cordage. Its sap yields a welcome 

 beverage, ^ and the fragrant and insect-resisting Russian 

 ' Holes are made in the trunk in the beginning of March, a large tree 



