Retrospective Criticism. 70'7 



Destroying the Scale on the Pine-apple, (p. 495.) — About six weeks back, I 

 sent a reply to Mr. Whiting's rejoinder to my paper on destroying the white 

 scale; but, as that pa])er has never appeared, and as there is a second 

 antagonist (Pro Bono Publico) in the field, I beg to offer a few remarks 

 on his letter, which, with your permission, I should like to appear as 

 a postscript to my former lucubration. [The letter, and the remarks, we 

 considered alike u.isuitable for this Magazine, and have thrown them aside 

 accordingly.] .... I feel no hesitation in asserting that the scale can 

 be destroyed by water in its most limpid state, though, I will admit, not without 

 running some risk of injuring young fresh growing plants. It now only 

 remains for me to add that I am the responsible author of all the letters that 

 have appeared in this Magazine under the signature of L. O. L., and that any 

 further remarks by Pro Bono Publico, or any other anonymous scribbler, will 

 be considered by me as beneath contempt. — W. P. Ayres, Sub-Gardener at His 

 Grace the Dulte of Devonshire's, Chiswick. 



Q,uercus Hobur sessiUJldra at Wobiirn Abbey, (p. 578.) — Mr. Forbes states 

 that we have been misinformed as to this kind of oak not having been recog- 

 nised in Woburn Park till last spring. He says, " I assure you the Duke of 

 Bedford has been well aware that both species were in the park for many 

 years. His Grace gave me instructions to mark the species several years ago, 

 and had even several of the trees cut down to ascertain the qualities of the 

 wood. I can also assure you that both kinds were closely examined by 

 Mr. Atkinson and myself in 1825." — Woburn Abbey Gardens, Nov. 2. 1836. 

 When we visited Woburn Abbey, in September last, Mr. Forbes was in 

 Scotland ; and the trees were pointed out to us by Mr. Ireland, the Duke of 

 Bedford's forester. We certainly think that Mr. Ireland stated to us that 

 Quercus R. sessiliflora vi'as only discovered last spring, and marked, at that 

 time, in consequence of the discovery; but in this we may be mistaken; and, 

 at all events we embrace the earliest opportunity of laying the facts of the 

 case before our readers. — \Cond. 



Oak Galls, (p. 498.) — Your correspondent R. L. of Surrey alludes to 

 " long strings of berries, similar in a great degree, particularly in colour, to 

 those of the pale red currant called the Champagne," being found on the oak. 

 I beg to notice that this appearance often occurs, though more plentifully in 

 some seasons than in others. It is one of the oak-gall insects which chooses 

 the slender stalk of the catkin to lay its eggs in, rather than any other 

 part of the tree. The gall insects are hymenopterous; that is, they have four 

 membranous wings, and the tail of the female is armed with a sting. These 

 flies compose the old genus Cjnips, of which five or six species are well known 

 in Britain. The first is C. glechmnce, usually found in the tubercles on the 

 leaves of the ground ivy ; 2. C. quercus gemvice, bred in the large imbricated 

 galls on the extreme buds of oak trees ; 3. C. bdccariim, in the small tubercles 

 on the under side of oak leaves : these are about the size of currants when 

 full grown ; 4. C. quercus folii, in the large tubercles (or apples, as they are 

 called) on oak leaves ; 5. C. quercus petioli, bred in the tubercles on the 

 petioles of oak leaves. 



I am uncertain whether this last be, or be not, the same species which 

 chooses the catkin for its nestling place ; but I am inclined to think not, as I 

 have often observed them distinct on the same branch. If the one noticed 

 by R. L. be not already described and namcLJ, C. quercus amenti may serve 

 as a distinction. I have bred all the flies from the different galls under close 

 glasses ; but, as it is many years since, I cannot speak with certainty whether 

 the C. quercus amenti be a distinct species or not. 



There is a remarkable fact accompanying the deposition of the eggs on the 

 dangling stalk of the catkins. These male flowers are destined to wither and 

 drop off as soon as their office of shedding the pollen is terminated; but if 

 before they have done so, they are seized, and appropriated by the fly, they 

 become i)erraanent, and remain so until the maggot within the gall ceases to 

 feed. From this circumstance, it is evident that the flow of the sap is in pro- 



