156 TKAXSACTIO-NS AND I'KOGEEDINGS OF THE [sess. LXIH. 



the climate. In order tliat it may not be grown over by 

 the thickening stem, the cells of the branch remain 

 merismatic where it passes through the cambium of the 

 mother axis, and increase in length takes place inwardly 

 equal to the breadth of the wood ring, and outwardly equal 

 to that of the bast. 



The branch of limited growth thus elongates in a 

 manner similar to that of a medullary lay. The interfoliar 

 bud develops only under the stimulus of an increased 

 supply of nutriment. This may occur — (1) if the phloem of 

 the shoot is damaged, and the elaborated sap consequently 

 cannot pass down beyond the seat of injury ; (2) if the 

 side branches are suppressed ; and lastly, if the end and 

 whorl buds of the shoot are destroyed. 



In the plantation to which I have already referred, 

 the pine shoot beetle (Hylcsinus piniixrcla) is very 

 common. The thinnings and other cut material were 

 allowed to lie in the wood, thus forming the best breeding 

 place possible for the beetle, which consequently appeared 

 in great numbers last spring. The adult beetle hibernates 

 in the cut material, and flight occurs in spring. The adult 

 attacks the young shoots, boring into them and tunnelling 

 out the pith towards the apex. The shoot is killed, 

 becomes dry, and is snapped off by the wind at the spot 

 where the insect began its operations. At a distance, the 

 tree looks as if it had been clipped with scissors, hence the 

 Germans call this insect the Waldgiirtner, or forest 

 gardener. Nearly every tree in the plantation lost a 

 great many buds in this manner. In most cases where 

 the leader had been destroyed, the developing interfoliar 

 buds gave the appearance of miniature witches' brooms 

 on the tree. This curious effect was produced by their 

 thick bushy growth and by the character of the needles, 

 which were short, -thick, and fleshy, and much lighter in 

 colour than the rest. A transverse section of those short 

 thick needles showed them to have an abnormal number of 

 resin canals, as many as eighteen or twenty occurring 

 in one leaf. A case is cited by Schacht — " Lehrbuch 

 d. Anatomic u. Physiologic," p. 121 — where as many as 

 twenty-four were found This great number he attributes 

 to the very luxuriant growth of the tree. A longitudinal 



