300 A FOREST TOUR AMONG THE DUNES OF GASCONY. 
the sand from being carried too far inland. A fresh layer of sand 
will then deposit itself over the plantation; and when this has 
occurred, and the surface has thus been restored, the artificial 
dune must be re-formed, and the sowings re-made. We were 
assured that no other course is possible. This is an excellent 
instance, showing what incessant care and watchfulness are 
required to carry out an undertaking of this kind successfully. 
TREATMENT OF THE CLUSTER PINE. 
On our way from Bordeaux to Arcachon, we left the train at 
La Teste, and walked across the dunes to our hotel. The forest 
consists of pure pine, felled in some blocks at sixty years, and in 
others at seventy-two years, of age; but oaks (Q. pedunculata and 
Q. Tozza) are now being planted among the pines. 
After breakfast, we visited the Mouleau block, situated at a 
distance of three or four miles in a southerly direction from 
Arcachon. Here we found that, as elsewhere, the forest had been 
naturally regenerated with great success, there being a dense crop 
of young trees, ten years old, and from 15 to 20 feet high, upon 
the ground. M. Boppe explained the system of treatment 
adopted for the cluster pine forests of this region, The tree has 
special requirements in the way of soil and climate ; it will not 
grow upon limestone, and it cannot stand cold down to one or two 
degrees above zero (Fahrenheit), if prolonged for more than a 
week ; neither can it be grown profitably for resin at any great 
distance from the sea. It is most important, in the case of this, 
as of other species, that before the tree is introduced into any 
locality a careful study should be made, in order to decide whether 
the conditions are such as will ensure success; and a forcible 
argument against the introduction of new species during extensive 
afforestation works is, that these conditions may not be fully 
known at the time. For instance, the cluster pine was exten- 
sively planted in the Sologne and in Normandy between the years 
1830 and 1880; but during the unusually cold winter of 1879-80, 
nearly the whole of these forests, covering in the Sologne alone an 
area of over 300 square miles, were completely killed off. 
This pine gives seed abundantly nearly every year, and its 
regeneration by natural means is very easy to effect. As we had 
previously noticed in the Maures, we found that, whenever the 
seed-felling had been made, there was almost invariably a plenti- 
