10 



EDWARD C. JEFFREY ON 



able number of roots of different species of the genus from the Arnold arboretum of Har- 

 vard university and from the Hunnewell pinetum at Wellesley, Mass., has revealed no 

 exceptions to this rule. The cells of the phloem in the root of Abies are sometimes very 

 small. As an example of this feature A. magnified may be cited. Sclerotic nests of cells 

 are somewhat constantly present in the so called secondary cortex of the root in Abies, 

 and may clearly be seen in figure 22. Resin ducts occur occasionally in the same situ- 

 ation, but there is never any communication between these and that which is present 

 in the first annual ring of the wood. 



In figure 24, plate 3, is shown a transverse section through the woody axis of the 

 cone of Abies appoint is. This is the only species of the Old World in which resin canals 

 have been found in the wood of the reproductive axis. Two cones, which as far as could 

 be learned were from different sources, showed this peculiarity. In the one figured there 

 are two rows of resin ducts present extending completely round the cone, although some- 

 what better developed on one side than on the other. Figure 25, plate 4, shows a portion 

 of a similar section more highly magnified. The resin canals in this case do not become 

 very large towards the top of the cone, as in A. magnified, but resemble those of the 

 former species in disappearing entirely at its base. The cells which surround the resin 

 canals are characterized by the presence of a small amount of tanniniferous material in 

 the form of minute granules, but they contain much less of it than do the cells of the 

 medullary rays. A. apollinis differs from A. magnified in that the resin ducts of the 

 wood of the stem are confined to the axis of the cone, and do not appear in the 

 first annual ring even of vigorous vegetative branches. The only other species of Abies 

 in which resin canals have been found in the cone is A. grandis, as has been described in 

 the first memoir. Here, however, the occurrence of the resin passages appears to be 

 sporadic, for they have only been observed in a single specimen and are absent in four 

 others. In A. balsamea, A. fraseri, A. concolor, A. dmabilis, A. nobilis, A. bracteata, 

 A. veitehii, and A. cephcdonicd no resin canals were found in the woody axis of the female 

 cone. A. nobilis was erroneously described in the first memoir as possessing resin ducts 

 in the wood of the female cone. The cone in which these structures were found turned 

 out to be incorrectly diagnosed, and was really A. magnified. Keteleeria in its anatomy 

 obviously belongs with Abies although it has the habit of Cedrus ; the wood of both vege- 

 tative and reproductive axes is entirely without resin canals. 



The leaf trace of Abies is often double, even in the lamina, and where a geminate 

 fibrovascular strand cannot be distinguished in the blade of the leaf, it can usually be 

 made out in the part of the trace which runs in the cortex. This, for example, is the 

 case in Abies magnified,, where the foliar trace does not give clear evidence of being a 

 double strand in the free flattened portion of the leaf. By following the trace down into 



