ANATOMY AND I MI V L< Hi KN V or TIIK ( 'ONIFERA LKS. 



17 



ences in the place of formation of the traumatic resin canals occur, as has been pointed 

 out above in the case of different species of Abies. Unfortunately ] have not had access 

 to material of the wood of (J. libani. The only specimens available were seedlings of the 

 species growing in the nursery of the Arnold arboretum, of Harvard university. None of 

 these showed injury, as they had been grown with great care. As a consequence they 

 were useless for my purpose. 



Another striking feature of figure 40 is the presence of a single horizontal resin duct 

 passing radially outward from the row of tangential ducts. In figure 41, plate 6, is seen 

 another example of a horizontal resin canal from the same material. The horizontal 

 ducts in the two figures just described ended blindly and did not communicate externally 

 with other similar ducts running in the vertical plane. Often, however, when two rows 

 of traumatic vertical canals occur near each other in the wood, horizontal ducts extend 

 from the one series to the other. Such an instance is clearly shown in radial section in 

 our figure 42. Very often these radial ducts conjoining different tangential rows of ver- 

 tical ducts, are very much larger in caliber than are the vertical ducts. This feature 

 appears clearly in figures 42 and 43, plate 6. In figure 43, the horizontal canal extends 

 beyond the second series of vertical ducts only to end at a short distance to the outside of 

 it. It should here be stated that the horizontal ducts, so far as my observations go, always 

 start with a series of vertical ducts and run radially outwards, ending blindly or joining 

 with a more exterior series of vertical canals. They never pass inward from a vertical 

 series of resin ducts, which is another argument for their being entirely a traumatic phe- 

 nomenon. Figure 44, plate 6, is a tangential section of the wood of Ceclrus deodar a in a 

 plane outside the vertical row of resin canals shown on the left of figure 43. It will be 

 observed that in addition to the small linear rays, which are normally present in the genus 

 Cedrus, there is a number of large, so called fusiform rays. Some of these enclose a resin 

 canal, while others do not. The smaller fusiform rays are cross sections of resin canals 

 which have ended blindly, while those which are of larger size contain obvious resin ducts, 

 which are becoming narrower of lumen, but which have not yet been occluded. 



Figure 45, plate 6, shows part of the transverse section of the axis of a cone of 

 Cedrus atlantica. In the row of bundles which occurs on the upper side of the figure 

 there are no resin canals in the woody tissues. The cavities, appearing on the outer sides 

 of the wood bundles, indicate the position of the collapsed phloem, the section being made 

 in this instance from dry material. Resin canals occur in the cortex only of the female 

 cone of C. atlantica. Cones of C. libani and C. deodara were examined with similar 

 results. In no case have I found resin ducts in the woody tissues of the cone in the genus 

 Cedrus. 1 



'Radais ('94) has, however, described resin canals in the first year's growth of the cone of Cedrus deodara. 



