156 



Zoology. 



in June cf was visited by Scolyti, perforated in many places , and, from the eggs 

 then deposited, now, September 9., teems with larvae, while a b c did not in June 

 receive a single perforation, and noiu does not contain a single larva ! 



This result satisfies my mind that the Scolytus destructor is altogether 

 guiltless of causing the death of healthy growing trees. Those who may 

 agree with me will discover another instance of the harmonies of nature, in 

 the season at which the Scolytus commences perforating, for the purpose of 

 depositing its eggs. This season is June or July ; and hy June or July the 

 processes of vegetation for the year have always determined and distinguished 

 the healthy growing trees from the sickly and the dying, and have thus 

 demonstrated to the Scolytus the materials most appropriate for hatching, 

 nourishing, and developing her offspring. 1 have seen insects much like the 

 Scolytus destructor in the bark of spruce fir, and in that of the ash and 

 other trees. The track made by the insect which lays its eggs in ash bark 

 is always horizontal, that is, at right angles with the direction of the stem 

 (fig. 31./), and larger than that made by the Scolytus destructor in elm 



bark (Jig. 30. e), whose track, besides being smaller, is always perpendicu- 

 lar, that is, parallel to the direction of the stem of the tree. Although out 

 of place here, I must not omit to remark that the oil of tar, applied by Mr. 

 Deck, as a preservative, to the Catherine Hall trees, proved inefficacious. 



I would notice as a fact in vegetable physiology, that in the tree ex- 

 perimented on {fig- 29.), the part immediately above b projects over b all 

 round, being 26 in. in circumference, while the part immediately below b is 

 but 22 in. ; this difference is the result of three seasons' growth. The part 

 projecting ovei- b exhibits, on its lower side, short pendulous granular excre- 

 scences, like incipient roots (fig. 29. g) ; and two queries have arisen in my 

 mind respecting it ; one, whether this gibbous projection is not partly owing 

 to nutriment absorbed into this newly formed part from the atmosphere; the 

 other, whether the root-like excrescences might not, by the application of 

 a body of moist soil about them, have been developed into actual and 

 effective roots, in the manner that any cutting or lajer forms roots, and 

 becomes a distinct plant. lam, Sir, &c. — J. Denson, sen. Waterbeach, 

 near Cambridge, Sept. 9. 1830. 



In our Gard. Mag., vol. i. pp. 378 — 382. will be found an interesting 

 article on the charges against the Scolytus, and in our remarks appended to 

 that article we shall be found of our correspondent's opinion. The present 



