ANATOMY AND PHYLOGENY OF THE CONIFERALES. 448 



originally the end of the yearly growth in length of the branch. In no case which has 

 come under my observation did the resin ducts of the first year's growth in one annual 

 segment of a branch become continuous with those in the next upper segment repre- 

 senting a subsequent year's growth in length. As a consequence the resin ducts of each 

 first annual ring form a closed system and are confined entirely to their own segment of 

 the branch. There are, further, no lateral anastomoses of the ducts in the same annual 

 ring. In the weaker lateral twigs of the branches from the three lots of material 

 mentioned above, resin ducts were generally found to be entirely absent. Through the 

 kindness of Prof. C. V. Piper, I received formalose material of the branches of a young 

 tree twenty years old, grown at Pullman, in the state of Washington. Not even the 

 largest and most vigorous branches in this material showed any indication of the presence 

 of resin ducts. Similar observations were made in the case of alcoholic specimens 

 supplied to me by Dr. A. A. Lawson, of the Botanical department of Leland Stanford 

 university. It may consequently be stated that so far as the present observations go, 

 the presence of resin ducts in the first annual woody ring of S. gigantea is confined to 

 the more vigorous branches of older trees which have already produced female cones, and 

 that the phenomenon is normally absent in the smaller twigs of large trees as well as in 

 the entire branch system of young trees. 



The Reproductive Axis of S. gigantea. 



In figure 6, plate 68, is seen the woody portion of the base of the female reproduc- 

 tive axis of S. gigantea in transverse section. In the first annual ring are numerous 

 large resin ducts similar to those described above in the case of the more vigorous vegeta- 

 tive shoots of adult trees. The second annual ring is very broad and is quite free from 

 resin passages. It is followed by a number of much narrower rings equally free from 

 resin canals. The peduncular portion of the reproductive axis of S. gigantea continues to 

 grow in thickness for some time after the seeds have been shed, and in this respect it 

 resembles certain species of Pinus with persistent cones, and at the same time presents a 

 marked contrast to S. sempermrens. Figure 7, plate 68, shows the center of the same 

 section more highly magnified. The size and distribution of the resin ducts and of the 

 resin cells also can be very well made out. Figure 8, plate 68, reproduces a cross section 

 of a higher region of the same peduncle. The narrow annual ring containing the resin 

 ducts seen in the last two figures, has disappeared, and the broad second ring of annual 

 growth now abuts directly on the pith. In figure 9, plate 69, there is represented an 

 intermediate region between those shown in figures 6, 7, and 8, of plate 68. Some of 

 the resin canals in this section are very much enlarged. This appearance is due to the 



