CONIFERALES 



319 



wood normally shows the presence of only radial parenchyma, lon- 

 gitudinal storage elements being absent. The longitudinal radial 

 section of the wood 

 (Fig. 226) shows 

 a condition of pit- 

 ting resembling that 

 found in the Cordai- 

 tales, namely, one 

 which is alternating 

 and characterized 

 by the absence of 

 the bars of Sanio. 

 The absence of wood 

 parenchyma and the 

 alternating char- 

 acter of the pitting 

 are features which at 

 first sight would 

 seem to justify the FIG. 225. Transverse section of the wood of Agathis 



assumption of a ^tstraiis. 



close degree of rela- 

 tionship between 

 the araucarian coni- 

 fers and the Cordai- 

 tales, and this view 

 of their affinities has 

 been the one almost 

 universally adopted. 

 Before we inquire as 

 to its validity it is 

 necessary to exam- 

 ine the organization 

 of Mesozoic repre- 

 sentatives of the 

 group. In Fig. 227 



FIG. 226. Longitudinal section of the wood of Ago- 1S snown m trans- 

 this australis. verse section the 



