242 



GYMNOSPERMS 



pits. They arc characteristic of the Abietaceae, and it has been 

 claimed that they are confined to this family, and that even here 

 they do not occur in Abies and Pseudolarix. However, they have 



Summerwood 



Spring wood 



Pifh ray. 



bngitudinal radia! section 



Fig. 248. — Finns slrobiix: cube of secondary wood, showing transverse, longitudinal 

 radial, and longitudinal tangential sections, and pith ray; at the right, the larger, 

 thinner-walled cells of the spring wood; at the left, the larger, thicker-walled cells of 

 the summer wood; X400. — From Coultkr and CiiAMuiiRLAiN, Morphology ofGymno- 

 sperms'^^ (University of Chicago Press). 



been found in wound tissue of Abies amabilis and A. concolor, and 

 they occur, sporadically, in a few species of Ta.xodiaceae and Cu- 

 pressaceae. Penhallow"" thinks the rare cases mark the beginning 



