126 



BOTANICAL GAZETTE 



[august 



Van Tieghem calls attention to the one-sided action of the cam- 

 bium in his work on Piper nigrum. 



Figs. 18, 19. — Fig. 18, section of peripheral ring of the bundles of P. methysticum 

 at a mature node, showing banded appearance of the rays, X35; fig. 19, tangential 

 section of peripheral bundles, showing branch gap; X7. 



The medullary ray becomes lignified and in longitudinal 

 section shows pitted cells. At the node in the largest stems avail- 



