Henkv and Flood — The Douglas Firs. 73 



transverse section shows llie proportion of breadth to thickness as 

 2'75 ; 1 ; epidermal cells of tlie under surface papillate ; hypoderm well- 

 marked in the centre al>()ve and beneath, occurring elsewliere in groups of 

 two or three cells; idioblasts few; resin-canals witli two layers of lining 

 cells; odour like that of the type, but less fragrant. 



Cones resembling tlie typical form in the straight and not reflexed bracts, 

 but snuxUer in size; scales fewer (about Lliirty) in -,% phyllotaxis, |- incli 

 wide, more concave internally. Bract with long terminal awn, and .'^hort 

 blunt lateral lobes. Seed smaller than in the type. 



This variety is intermediate in the characters of the leaves between the 

 Oregon and Colorado species, but is closer to the former, which it resembles 

 in the cones. The Howers have not been seen by us. 



Var. cafsift was the name given by Schwerin to the Douglas Fir occurring 

 in the interior of British Columbia, at Quesnel, on the Upper Eraser Bivcr, 

 lat. 53°, where the climate is cold and comparatively dry. This variety 

 extends throughout the northern Kocky Mountains region of the Douglas 

 Fir, which includes the interior of southern British Cohnnbia, north-eastern 

 Washington, northern Idalio, and north-western Montana. 



The climate of this region is not so humid as on the PaciKc Coast, the 

 annual rainfall being 20 to 40 inches, falling mainly in the growing season. 

 The winter is very dry and cold, tlie temperature sometimes falling to -25° F. 

 A considerable number of the Coast conifers also grow in this region, notably 

 Abies ffrccndis, Western Hemlock, and Thuya (jujantea. Pinus poiiderusa, 

 rather rare in the Coast belt, becomes here an important constituent of the 

 coniferous forest. Larue occidcntalis is confined to this region. 



Attention has recently been called^ by Professor John Davidson, r.LS., 

 Vancouver, B.C., to the occurrence of manna on the foliage and branchlets of 

 this variety of the Douglas Fir in the dry belt of British Columbia, especially 

 in the valleys of the Fraser and Thompson rivers near Lyttou, Lillooet, 

 and Nicola. This manna is composed mainly of the rare sugar, melezitose. It 

 is produced in considerable quantity, and is not due to the attack of aphides, 

 being, apparently a natural exudation from the leaves. It is comparable to 

 the MaiiHC dc Brlam;uii, which is occasionally found as an exudation on the 

 leaves of the European larch in the French Alps "in the height of summer 

 and in the early part of the day." Melezitose is not known to occur in any 

 other conifer. 



In 1907 young trees of var. cacsia were raised in German nurseries from 

 seed gathered at Quesnel iu the preceding year by Baron von Fiirslenbeig. 



' See Amp.riciin Furestiij, February, 1920, p. 85 ; Scientijir Ameficau, 14 Februaiy, 

 li»20, p. 105 ; and Fluckiger aud Haubury, Phai-macuijiui.hUi, -klU (1870). 



