328 



THE ANATOMY OF WOODY PLANTS 



We may now turn to the brief consideration of evidence derived 

 from the organization of the wood of fossil forms and bearing on 

 the respective antiquity of the Abietineae and the Araucariineae. 

 The investigations of recent years have brought to light in the 

 Jurassic and Cretaceous numerous coniferous woods which to a 

 large degree possess characteristics intermediate between those 



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w 



FIG. 236. Transitional region from the xylem of the cone of .Piwws pinea 



of the Abietineae and Araucariineae. The conclusion naturally 

 follows that the two subtribes were less remote from one another 

 in Mesozoic time than they are in the present epoch. The question 

 of interpretation is strongly debated in the case of these woods. 

 The mass of paleobotanists, obsessed by the araucarian hypothesis 

 of the derivation of the Coniferales from their cordaitean ancestors 

 and little concerned with the fundamental principles of comparative 



