8 



EDWARD C. JEFFREY ON 



different examples of the large cones of A. magnified, three of which were from entirely 

 different sources. Rows of resin canals such as appear in figure 14, occurred in all of 

 them. Special care was taken to observe whether the cone or its peduncle had suffered 

 injury in any of these examples ; but in all the cases examined both organs were quite 

 normal in every way. Figure 15, plate 2, shows a part of another section of the same 

 cone as that shown in figure 14, more highly magnified. The plane of section in this 

 case is lower down in the cone, and the figure as a consequence, although under a 

 greater magnification than the preceding one, shows the resin ducts of smaller size. The 

 resin ducts become fewer and of less caliber as the base of the cone is reached, until finally 

 in the peduncle, or even above the actual peduncle, they disappear altogether. If instead 

 of progressing towards the base of the cone, one moves in the opposite direction, the 

 resin ducts instead of becoming fewer and of smaller size, are found to have larger lumina 

 and to become more numerous. The larger ducts of the upper part of the cone by reason 

 of their greater size and close proximity tend to become fused with one another, as is 

 clearly shown in figure 16, plate 2. The resin secreting cells which surround the resin 

 ducts of the woody axis of the cone in the species under discussion are thick walled and 

 are quite similar to those surrounding the resin passages in the wood of Larix. Thin 

 walled, resiniparous cells are, however, occasionally found where a resin canal abuts 

 directly on a medullary ray. Although a good deal of brown tanniniferous secretion 

 is found in the medullary rays of the cone, little or none appears in the parenchymatous 

 cells surrounding the resin ducts. 



In the memoir on Sequoia reference is made to the fact that resin canals occur in the 

 first annual ring only of vigorous shoots, in the case of trees which have already pro- 

 duced female cones. Interestingly enough, the same state of affairs has been found by 

 the writer in the case of the present species. Figure 17, plate 3, reproduces the two first 

 annual rings and part of the third in a cone-bearing branch of A. magnified from the col- 

 lection at the Arnold arboretum of Harvard university. I am indebted to Mr. George S. 

 Shaw and Prof. Charles S. Sargent for the opportunity of examining authentic material 

 of the present aud other species studied in connection with the present work. The 

 magnification is just sufficient to show the presence of resin ducts which are entirely con- 

 fined to the first annual ring of the four year old shoot in question. There was no evi- 

 dence of any injury to the branch, so the presence of the ducts must be regarded as a 

 perfectly normal feature, especially in view of other similar observations shortly to be 

 recorded. In the stouter lateral branches of the shoot in question there was in some 

 instances a similar occurrence of ducts in the first annual ring ; but in the more delicate 

 twigs these were entirely absent, thus duplicating the similar phenomenon found in 

 S. gigantea. Figure 18, plate 3, shows the structure of the first and second annual rings 



