CONIFERALES 353 



in the region of the secondary wood near the primary xylem, and, 

 where the pitting is abundant, frequent opposition of the pores. 

 In other words, a situation presents itself which is the exact con- 

 verse of that found, for example, in the Ginkgoales, in which the 

 primitive region of the secondary wood shows alternating pitting 

 and no bars of Sanio. In the later-formed wood the pits begin 

 to appear in opposition and are separated by bars of Sanio. If 

 we are justified in regarding the type of tracheid found in Ginkgo 

 as originating from that typical of Cordaitales and other ancient 

 gymnosperms, we are similarly warranted on the same evidence 

 in viewing the alternation of pitting and the absence of bars of 

 Sanio in the adult wood of the existing araucarian conifers as 

 derived from a state in which both opposition of pitting and bars 

 of Sanio were present. The evidence supplied by fossil forms, 

 moreover, justifies the derivation of the Araucariineae from abie- 

 tineous forbears, since many distinctly araucarian woods have 

 been discovered in recent years in the Mesozoic which clearly 

 present either normal or traumatic features uniting them, with 

 the Abietineae. In some instances, for example, thick-walled, 

 heavily pitted ray cells, similar to those commonly characteristic 

 of radial parenchyma in living and fossil Abietineae, are found in 

 Mesozoic araucarian woods. This feature is significantly paral- 

 leled in the rays of the cones of living araucarians. Traumatic 

 resin canals are also found commonly in woods which are transi- 

 tional from the abietineous to the araucarian type. This is notably 

 the case in Brachyoxylon, a very common Mesozoic type of wood, 

 and also in the much rarer Araucariopitys. Normal resin canals 

 are, moreover, found in the wood of the ovuliferous cone of the 

 living Agathis Bidwillii, from Java. It has been stated in earlier 

 pages that there is distinct evidence from the organization of 

 actual fossils and from the structure of conservative, regions in 

 the existing Araucariineae that abundant wood parenchyma was 

 an original feature of organization of the araucarian as contrasted 

 with the abietineous Coniferales and the Ginkgoales, in which 

 tangential storage elements are conspicuously absent. 



Not only, however, have abietineous forms obviously given 

 rise to the araucarian stock on the basis of the general principles of 



