194 THINNING. 



them, so that they are cut down as mere weeds before 

 they can possibly be of useful size, or if not cut 

 down till of useful size, the loss is still greater, as in 

 the present case. The extra labour of thinning and 

 clearing the thinnings out of the plantation entailed 

 expense almost incalculable, as will subsequently be 

 shown. 



The evil consequences of general mixing, in con- 

 trast with that of grouping, may be seen in this plan- 

 tation. One part of it, a year younger than the other, 

 was nearly all planted with larch, while the other 

 part, as already shown, was of a general mixture. 

 The soil, exposure, altitude, &c., are alike in both, yet 

 the difference was altogether in favour of the part 

 slightly mixed. The trees, by making allowance for 

 the difference of age (one year), were scarcely so tall 

 as the others, but were more proportionably grown and 

 without any appearance of disease ; while the larches 

 in the general mixed part were all but exclusively 

 diseased, being covered with ulcer. 



In the general mixed part the bark of the larch is 

 black, as if dusted over with soot : numerous larch 

 aphis infest them all, and ulcer is upon most of 

 them. The spring frosts of April 1859 browned the 

 foliage of nearly all the larches in the plantation in 

 both parts ; but while those ;partially mixed with pine 

 and spruce soon recovered without sustaining any 

 visible hurt, the other part, or that completely mixed 

 and overcrowded, was so severely injured that most 

 of them lost their leader, while hundreds were quite 

 killed. The difference of effect produced seems only 

 to be accounted for on the ground that the one part 

 being healthy and of vigorous growth, was able to 

 ward off the injuries ; while the other, being already 



