DISEASES. 245 



never observed the two diseases winch attack those 

 trees in your country. All my Alpine correspondents 

 agree with me on this point, and have never seen any- 

 thing of the kind. Moreover, we can even name the 

 larch as the Alpine tree which is less liable to disease 

 than any other. There is a peculiarity which all per- 

 sons accustomed to observe these trees have been struck 

 with, namely, that the trunks are remarkably healthy. 

 They are, in particular, rarely attacked by the der- 

 mestes, which are so formidable to firs. Sometimes, 

 but very seldom, we see a small caterpillar devouring 

 the leaves, but no damage results from it. M. de 

 Charpentier has even seen in the Yalais, in July 

 1820, all the trees from the Yalley of Conches to the 

 bottom of that of Ferset, bereft of their leaves through 

 the same cause, but none of those trees perished. 

 Sometimes also we see the larches having a wound or 

 resinous cancer, but it does not present the regular 

 symptoms which you describe. On the contrary, it 

 seems to proceed from some accidental cause, such as 

 a blow or knock, which the tree may have received 

 when it was in full sap. 



" All these observations incline me to think that the 

 cause of the diseases which attack your larches must 

 be sought for in some difference existing in the physical 

 nature, or in the culture of your trees and ours. We 

 do not think that the nature of the soil should have 

 a very marked influence, for the larch is not particular 

 about the soil where it grows, and seems only to fear 

 extremes, which are fortunately rare. Marshy grounds 



