iqiq] 



BELYEA— SEQUOIA 



471 



parenchyma cells of the ray. There is also evolved a radial elonga- 

 tion and projection of the terminating ends of the vertical tracheary 

 elements in direction parallel to and in contact with the paren- 

 chymatous cells of the ray, with communicating pits in the inter- 

 vening walls, as is shown in fig. 3. Inasmuch as true ray tracheids 

 are not to be found, it is believed that these structures are acting 

 as such and possess all the functions attributed to and carried on 

 by ray tracheids. 



Fig. 4. — Radial section (second growth) showing wood tracheids bent and pro- 

 longed to form marginal ray tracheid two cells deep for width of two vertical wood 

 tracheids. 



It is also to be noted that in a great many cases the course of 

 the bent-over and prolonged tracheid is imitated by those imme- 

 diately contiguous with greater or less development. This is 

 especially noticeable in fig. 4, where two neighboring and con- 

 tiguous vertical tracheary elements are bent over in such a way that 

 a ray tracheid two cells deep is evolved for the distance covered 

 by two vertical tracheids. That these bent-over wood tracheids 

 function as ray tracheids is evident from the double form of pitting 

 to be found in their cell walls. 



