406 Retrospective Criticism. 



lower than themselves. To attain this size, they will require from four to 

 seven years, according to the quality of the soil." By the way of encourag- 

 ing this practice, he adds, in p. 224., that " young oaks, thus sheltered from 

 the outset, will make more progress in five years, than unsheltered ones will 

 do in ten years." I think this somewhat doubtful : but, be that as it may, 1 

 deny that the quality of the wood in the one case can be any thing like equal 

 to that in the other ; for, as oak grown in milder climates is admitted to be 

 possessed of less durability than oak grown in the mountains of Scotland and 

 Wales, the same results must ensue, if by extreme sheltering we shall assimilate 

 the temperature of those last-mentioned parts to that of the former. 



It is useless to talk of the deleterious effects of spring and autumnal frosts 

 upon young oak plants : this last spring the frost was severer towards the 

 middle and latter end of May, than we have experienced these some years 

 past ; the two years' seedling larches suffered a little in consequence, but not 

 a single oak was injured, although I observed the half-expanded foliage of 

 several young oak quarters white with the hoar-frost. Now these, I presume, 

 were preserved by their not being brought unduly into leaf; but, being only 

 acted upon by the natural impulse, they thus acquired a sufficient degree of 

 hardiness as they advanced : but, farther, the buds on the shoots of a full- 

 grown oak tree are just as tender when about bursting forth in spring, as is 

 the seedling when rising through the ground ; yet how seldom, if ever, do we 

 see the head of a large tree affected by frost ! Can we attribute this to any 

 thing else than to the absence of an undue excitement on the vegetative 

 powers, such as is produced by too close shelter. To me it appears no difficult 

 task to find the medium between the two extremes mentioned, and this me- 

 dium, I conceive, Mr. Bree has struck exactly, by planting oak a few years 

 before the nurses. A firm and perfect nucleus is thus prepared, whereon to 

 deposit the future concentric layers of sapwood ; and these in their turn will 

 be converted into sound timber the more readily and certainly, from nature 

 having been allowed to communicate in her own way that state of soundness 

 to the heart wood, which is so necessary for regulating the fluid system, and 

 for ultimately completing the vegetable structure. 



When a plantation of young oaks has stood two or three years without 

 nurses or shelter, and is found to be alive, we may consider them as having 

 fairly established themselves in the ground. A moderate admixture of firs 

 ought then to be introduced, in such quantity as would draw up the oak along 

 with them, without producing an unnatural elongation of trunk ; but, before 

 Mr. Bree's system of treatment can be aeted upon with safety, I am of opinion 

 that the plants will require to be raised on principles somewhat different from 

 those commonly acted upon at present. 



Had your pages permitted, I should have added a few hints on the treat- 

 ment of plants, intended to be put out without nurses ; the age and size, 

 method and time of pit-making, &c, but this 1 shall reserve for a future com- 

 munication. — James Munro, Brechin Nursery, June 16. 1834. 



The Influence of the Stock on the Scion. — You doubted the fact of the 

 shaddock becoming sweet, when engrafted on a sweet orange ; or rather hinted 

 at the improbability of a union between two trees so opposite in their genera ; 

 and declared the impossibility of the orange becoming red, when engrafted on 

 the pomegranate of Malta. Facts of the union of trees quite as dissimilar as 

 the above are on record, and, I presume, the authorities on which they are 

 related will not be impugned. I met with them four years since. " A large 

 green plum, grafted on the stem of the long black fig, succeeded at Rome." 

 (Letter of John Ford to Mr. Ellis. Linncean Correspondence, vol. iii. p. 64.) 

 " The Chionanthus virglnica was successfully grafted upon the common 

 ash, a tree of the same natural order with itself, but not of the same genus." 

 (Sir J. E. Smith. Linncean Correspondence, vol. iii. p. 454.). — J. M. Phil- 

 adelphia, May 11. 1834. 



Our correspondent alludes to the following paragraph, which appeared on 

 the wrapper of our 45th Number : — " An American correspondent would be 

 glad to be informed in what work (for he thinks he has seen it somewhere) it 



