472 



BOTANICAL GAZETTE 



[DECEMBER 



This procumbent and radial prolongation of vertical tracheary 

 elements is to be found on either the upper or the lower margins 

 of the rays. The direction of the prolongation may be toward the 

 pith or toward the cambium. There seems to be absolutely no 

 constant feature of direction which the bending shall follow, either 

 in orientation of the one with the other or with the pith and the 

 cambium. Along the same ray, as is seen in fig. 5, neighboring 

 tracheids can be found bent in opposite directions and so pro- 

 longed that the end walls are in contact. 



Fig. 5. — Radial section (second growth wood): adjacent wood tracheids bent in 

 different directions along same ray. 



In this second growth wood these structures were com.mon to 

 all parts of the stem, pith, medial sections, and cambial layers. 

 Of the three it was perhaps least highly developed in the sections 

 contiguous to the pith, in which there is some development of 

 heartwood. It was found in equal frequency in either the spring 

 or the summer wood, although, as would be expected, it was more 

 clearly defined and capable of better figuring in the large structures 

 of the early wood. 



These structures recall and are similar to those described and 

 figured by Thompson (7) in the cone axis of Pinus Strobus, and by 

 Jones (5) in the mature wood of Sequoia sempervirens, in both 

 of which there is ascribed similar function by the respective writers. 



