AUGUST] 



BOTANICAL GAZETTE 



116 



radial longitudinal sections of the large medullary ray with its 

 included foliar strand. A careful study of a series of such radial 

 sections through the trace has made it apparent that this connection 

 is by means of long, irregularly shaped scalariform tracheids which 

 are the real tracheids constituting the trace, and not mere con- 



FiG. 3. — Radial longitudinal section of portion of large medullary ray with 

 included foliar strand: //, peculiar tracheidal formation apparently resulting from 

 fusion of two or more tracheids; rt, irregularly reticulated elements; X90. 



necting elements, as generally believed. These vessels may be 

 entirely scalariform in structure, or may change gradually from a 

 reticulate type at their tapering ends to decidedly scalariform 

 throughout the greater part of their horizontal and vertical extent. 

 As they extend horizontally through the gap they are arranged in 

 order of formation, one vessel beneath the other (figs. 4, 5), the 



