ANATOMY AND PHYL0GEN1? OF THE CONIFERALE8, 



■110 



around the medulla. Whenever a double system of ducts extends more or less com- 

 pletely around the wood of the scale, the series nearer the medulla is always complete, 

 whatever may he the ease with the more external series. The more complex arrange- 

 ments of the resin canals just described are more often found in the upper scales of the 

 cone. The outer system of ducts, unlike the inner one, never extends down into the 

 axis of the cone, although it may pass far up in the bundles into which the fibrovascular 

 tuhe of the base of the scale breaks above. 



In figure 13, plate 69, is seen a transverse section of the upper broad portion of the 

 fructiferous scale. The scale is covered on both the upper and the lower surfaces with a 

 layer of •periderm. In the fundamental tissue of the scale are numerous large resin 

 passages as well as numerous sclerenchyinatous cells. There are present two systems of 

 fibrovascular bundles oriented in opposite directions, of which the upper series is less well 

 developed and consists of somewhat smaller bundles. Along the upper margin of the 

 lower set of bundles, which are the better developed, can be seen small, light dots which 

 mark the position of interfascicular resin ducts. These are continuous with those 

 described above as occurring in the lower portion of the woody skeleton of the scale. 

 Resin canals are much more commonly present in the lower series of bundles of the 

 flattened upper part of the fructiferous scale than they are in the upper series, possibly 

 on account of the greater robustness of the former. Figure 14, plate 69, shows a 

 portion of the same section more highly magnified. The structure of the fundamental 

 tissue can be more clearly seen. It consists of parenchymatous elements, of long scler- 

 enchyinatous elements present in cross section, and of large resin passages. Within the 

 inner boundary of the woody tissue of most of the lower bundles can be seen one or more 

 resin ducts. These are absent from the upper bundles. Figure 15, plate 69, represents 

 another part of the same section. The fundamental tissue presents no difference from 

 that shown in the preceding figure ; but the bundles which belong to the lower series, 

 towards the margin of the scale, are obviously united by strands of tissue running 

 from their inner borders. The tissue in question is made up of transfusion cells. The 

 smaller terminal bundles of the extreme upper portion of the fructiferous scale of 8. 

 gigantea are all more or less completely united at their inner borders by transfusion 

 cells. The bundles likewise frequently terminate in transfusion tissue as well. Occasion- 

 ally towards the lower part of the course of the bundles, as they become united into the 

 fibrovascular tube of the base of the scale, the enormously developed transfusional borders 

 of the bundles bend inwards and fuse more or less completely together, giving rise to a 

 peculiar pseudomesarch type of bundle such as is shown in figure 16, plate 69. In this 

 figure, two resin canals are to be seen in the secondary wood. Subtending the part of 

 the secondary wood containing the two resin ducts, is a mass of parenchyma which is 



