DESTRUCTION OF TREES FOLLOWING CHARCOAL BURNING. 163 



According to the views of M. Perris, in the destruction of many of 

 the trees, they were enfeebled by the destruction of leaves and leaf- 

 buds ; they were thus brought into an abnormal condition, and then, 

 having become food attractive to lignivorous insects, they died in 

 consequence of their ravages. And when other means than the 

 primary ravages of the leaf devouring insects produce like effects 

 to those thus produced by them, like consequences may follow. 



Sect. III. — Destructive Consequences following the Effects of 

 Charcoal Burning. 



Professor Bagneris remarks in regard to a disease to be found in 

 certain plantations : 



" Frequently a pine is seen to wither and die, and the disease then 

 seems to spread in a circular form, the diameter of which gradually 

 increases. I have not been able to find out the cause. In Sologne 

 origins more or less imaginary were assigned to this. May not this 

 disease be caused by a fungus attacking the woody tissue % The form 

 it assumes would lead one to suppose so, and the curative means 

 employed strengthens the belief. In the Landes, a trench of 

 - 70 metres in depth is dug all round the place attacked, and the 

 circle of disease spreads no farther." 



The following observations throw additional light upon the 

 phenomenon, and seem to reveal the origin of the evil ; if they do 

 not determine also the- question raised as to the possibility of a 

 fungoid growth contributing towards the destructive result : 



" In the district of Orleans", says M. Boitel, " the maritime pine does 

 not present that vigorous production which in the south it owes to a 

 soil and a climate which are particularly favourable to it. The sands 

 of the Sologne are often deficient in depth, and when thence it comes to 

 pass that the tap-root of the maritime pine comes upon a bed of tenacious 

 and impermeable clay, the tree begins to languish, and its trunk and 

 branches become covered with mosses and lichens. A good many pine 

 woods find themselves in this condition when only fifteen years old. 

 The trees stand out against the evil till they reach the age of twenty or 

 five and twenty years ; but beyond that they become stationary, and 

 if they do not necessitate exploitation they are liable to be invaded and 

 destroyed by insects which become developed in innumerable swarms 

 in the bark and the wood. 



" It has often fallen to my lot to ascertain and verify ravages thus 



