254 ELEMENTS OF SYLVICULTUEE. 



considerable, if we balance against it the protection 

 which it affords for all the country behind the dunes. 

 Nearly the whole of it is absorbed by the erection 

 and constant repair of the paling, and this principally 

 by the transport of planks and brushwood over a 

 long length of uneven country formed of deep and 

 yielding sand. 



It now remains for me to describe the treatment 

 of the Cluster Pine for the extraction of resin. But 

 before I do so, I must mention that since the dunes 

 have been wooded, the hollows have dried up. It is 

 difficult to say whether this is due to the transpira- 

 tion of the leaves, or rather to the absorption of the 

 water by the vegetable mould, or whether it is to 

 be attributed to some other cause or causes still 

 unobserved. In consequence it has been possible to 

 restock those valleys where no grazing took place, or 

 in which grazing was forbidden. 



It is an established fact that the extraction of resin 

 is never remunerative unless the pine is in its true 

 habitat. It is only in hot and mild climates that 

 this tree is indigenous. It is common on the west 

 coast between the mouths of the Adour and the 

 Gironde. To the north of the latter river, between 

 Koyan and Eochefort, its vegetation is less vigorous 

 its wood is less resinous, and it no longer attains its 

 usual size. Moreover, the forests it forms are not so 

 dense. Further north, especially in the valley of the 

 Loire, where plantations of it have, in my opinion, 

 been too largely made, we get completely out of its 

 station. It no longer propagates itself naturally, it is 

 much shorter-lived, its wood is of an extremely 



