DISEASES. 249 



all trees, vegetation begins to be feebler. I cannot so 

 well perceive the connection of these general facts 

 with the ulceration of the bark. 



" If, after these observations, I dare to hazard some 

 ad\T.ce concerning a country I do not know, this is 

 what I would say: First, I have no doubt that the 

 elevated parts of your country are more suitable than 

 the lower, provided the ground be neither too dry nor 

 too hard, I need not add nor too marshy, for that is a 

 fact well known. Second, I think that your decli- 

 vities would do better than summits, and particularly, 

 if you have tops of mountains covered with turf and 

 marshes (as in some parts of Belgium) ; the declivities 

 below which will be the best. In our country, we 

 observe that the larch grows better in those parts ex- 

 posed to the north than to the south. The difference 

 is sometimes so striking that, in the valleys parallel to 

 the equator, it is not rare to see all the side to the 

 north covered with larches, and none at all to the 

 south. I am inclined to believe that this arises from 

 the irregularity of our spring, which causes the buds 

 of the larches to be too precocious in the southern de- 

 clivities, and, consequently, they are frequently frozen. 

 This happens to our walnut trees, which, although 

 they are affected by the frost, grow better on the 

 northern decli\TLties than on the southern, where their 

 buds, being too forward, are frozen. In your latitude, 

 where the spring is more regular, I think this cause 

 will not operate ; and I would say that, if the southern 

 declivities be not too dry, the larches will succeed 



