EXTRACTS FROM PROCEEDINGS. 



Ixv 



its leaves, until the whole turns brown and dead. The ravages of 

 the insect are evidently confined to the tissues external to the 

 hard wood ; for I have not yet seen an instance in which the wood 

 has been penetrated. The insect bores a perfectly round minute 

 hole through - the hard outer bark ; and when this is looked at, at 

 an early period after perforation, there is always found an exuda- 

 tion of turpentine, dried and brittle, but projecting about the -J-th 

 to Jth of an inch in extent, the free extremity trumpet-shaped, but 

 open and communicating with the perforation in the bark by a 

 passage from the free extremity. If the perforation in the bark 

 be traced further, it will be found to communicate with " a 

 burrow " or " run " under the bark, the direction of which is 

 chiefly upwards and somewhat tortuous. My belief is, that 

 thousands of these insects burrowing between the wood and 

 bark, at last entirely destroy the vital connexion between the 

 two, and thus the tree is destroyed ; for when the tree is dying or 

 nearly dead, if the bark be stripped off, it is found to be perfectly 

 dry and separated to a very great extent from the wood by nume- 

 rous subterraneous passages or runs. 



The insect, as far as I can observe, solely attacks the Scotch fir. 

 I have not seen any very old tree yet affected thus ; but trees of 

 thirty years' old have been destroyed, and many as young as ten to 

 twelve years. I have many now on my ground in which the stages 

 of attack and death may be witnessed. 



I have not been able, from want of leisure, to detect the insect, 

 and can give no information on the subject, and I have only ob- 

 served its ravages for some five or six years. If it continues it will 

 seriously affect the growth of Scotch fir in our neighbourhood ; 

 but with the opportunities of planting Douglas pine more cheaply 

 hereafter, we shall, I believe, be gainers in the end. 



Yours sincerely, 



Geo. Pollock. 



Harpenden, St. Albans, 

 May 30, 1868. 



Sir, — I herewith enclose the Agenda-sheet, with the title of a 

 subject proposed for the consideration of the Scientific Com- 

 mittee. 



It is obviously imj)ossible adequately to indicate the range and 

 bearing of a subject in a short title, nor can I hope to afford 

 sufficient explanation in a note ; but I shall be glad to go further 

 into the matter at the next Meeting of the Committee, if desired. 



