104 THE CANADIAN NATURALIST, [Dec. 



The bark of this tree is whitish upon the branches, but on the 

 old trunks it appears as a corky tissue, ferruginous-brown in color, 

 with a scaly rhytidoma, cracked in all directions, and separating 

 in whitish-gray plates. Some have supposed that both the speci- 

 fic and vulgar names of this tree are derived from the whitish 

 color of its bark. 



The leaves are from six to ten lines in length, and about 

 three fourths of a line in breadth, ordinarily curved, presenting 

 few stomata on both surfaces, summit acute, but much less so than 

 is the leaf of Ab ies (Picea) Menziesii ; section of the leaf quadran- 

 gular, presenting two resiniferous ducts larger tj^an those of 

 P. nigra. The leaves of P. alba are much more robust than 

 those of P. nigra, but their size varies very much, even upon the 

 same individual ; the same is true of the form, which is also very 

 variable. 



The male catkins are ovate, not pedicellated, about six lines 

 long ; length of the anthers one line. Female flowers in cylindri- 

 cal catkins, violet-red in color, and ten lines in length. Cones 

 cylindrical, reddish-brown, from one to two and a half inches in 

 length, numerously disseminated at the extremity of the branches, 

 and in the axils of the leaves ; scales thin, six lines long, rhom- 

 boidal, entire, slightly indented at the summit. Seeds small, 

 brown, a line long, with an oval wing of a very pale yellow color, 

 three times that length ; embryo with from six to eight 

 cotyledons. 



This tree in the vicinity of Quebec blossoms about the end of 

 May, and its fruit ripens in the autumn of the same year. 

 The warmth of the following spring-time opens the scales of the 

 cones, and liberates the seeds. These require for their germination 

 about twenty days ; twelve days later the young plant escapes 

 from its envelopes, and appears with its numerous cotyledons, 

 which resemble precisely the other leaves. The plumula of the 

 young plant is not apparent before two or three months. 



The wood of the white spruce is very white, compact, and 

 harder than that of the white pine (Pinus strobus). The 

 annual rings are sometimes three lines in breadth, and are 

 for the most part strongly marked, the autumnal wood being dark 

 colored. The medullary rays are composed of a layer of uniform 

 cells (figures A. and B, p. 109). The resiniferous canals (figure c.) 

 which are distinguishable by the aid of a magnifying glass, furnish 

 an excellent characteristic, and a ready means o distinguishing 



