ANATOMY AND IMIYUXJKNY <>K TFIK OONIFERALES. 



451 



In figure 26, plate 71, is shown a transverse section of a young branch of 8. semper- 

 virens from material sent to me by Dr. A. A. Lawson of the Botanical department of 

 Leland Stanford university. The bases of four leaves clearly appear on the margin of the 

 figure. These originate from the branch by a flat base in contrast to the rounded mode 

 of origin found in S. gigantea. In two of the leaves there are obviously three resin 

 canals in the mesophyll, another point of contrast to IS. gigantea and most of the other 

 Taxodineae and Cupressineae, where there is as a rule but a single resin duct in the 

 parenchyma of the leaf, and immediately under the fibrovascular bundle. The material 

 from which the illustration has been made was cut and preserved in California on the 

 2d of May. The growth of the present year's ring of wood has begun and has already 

 reached a considerable thickness. Branches of S. gigantea cut from trees at the same 

 spot and at the same time show scarcely any signs of the commencement of cambial 

 activity. The slowness of initiation of cambial activity in the Big Tree is no doubt one, 

 at least, of the causes of its greater hardiness. There are no resin ducts to be seen in 

 the wood of the young branch, appearing in transverse section in the figure, and in this 

 respect the illustration might stand for any branch of S. sempervirens ; for I have not 

 found even in the most robust ramifications of the mature trees of this species any indica- 

 tion of the resin canals, which are so often present in the first annual woody ring of >S'. 

 gigantea. 



Tkaumatic Resin Ducts in 8. sempervirens. 



In some of the specimens sent me by Dr. Lawson from the arboretum of Leland 

 Stanford university the phenomenon of fasciation was present. As this feature of S. 

 sempervirens has recently been fully described by Pierce (Studies on the Coast Redwood, 

 Cal. acad. sci., 1901), it will not be necessary to refer to it here. The wood in most of 

 the fasciated specimens was quite normal as regards the absence of resin canals; but 

 in the subterranean portion of a dead branch which had taken on the flattened mode 

 of growth so characteristic of fasciation, numerous resin ducts were found in tangential 

 rows. The shoot in question had obviously been injured and the appearance of resin 

 canals is doubtless to be correlated with the diseased condition of the tissues. Figure 

 27, plate 71, is made from a section through this branch. There are two annual rings 

 present and it is in the first of these that the resin ducts are to be seen. The ducts are 

 in tangential rows and are situated in the autumnal wood just as in figure 25, plate 71. 

 In figure 28, plate 71, are represented some resin canals from another section of the same 

 material, highly magnified. The resin ducts are obviously surrounded for the most part 

 by cells still containing protoplasm and a nucleus, although in some cases the tracheids 



