52 



BOTANICAL GAZETTE 



[JULY 



development 



twigs is also m 



ma 



and tissue devoid of vessels. This process of 

 reduction is least conspicuous, however, in the vicinity of the 



and in the five pairs of wide rays whic 

 segments from the wider wedge-shaped 



is not uncommon, therefore. 



It 



r- ••,-- 



* * 



.* -• 



the cross-section of a young twig that 

 during their first activity the so-called 



of the cambium 



formed 



stem 



ma 



A 



B 



C 



Fig. i. — A , tangential section seriate r 



of a young root of Fagus, show- c l us ters - 

 ing the vascular elements of two 



rootlets connected by a multi- m ^ttgUS 



seriate ray; B, Quercus (sub- sheets of 



sels in others. As in the case of poorly 

 nourished seedlings, stimulating types 

 of injuries or increased vigor recall the 

 multiseriate rays in those radii of the 

 stem in which they have suffered sup- 

 pression or disintegration. 



In vigorous young roots, wide multi- 

 seriate rays radiate outward from the 

 clusters of protoxylem. These rays, as 



grandifolia, form 



nn a 



which connect 



genus Erythrobalanus), showing 

 incipient stages of the disin- 

 tegration of a wide multiseriate 

 ray; C, Quercus (subgenus Lep- 

 idobalanus) , showing vestiges of 

 a multiseriate ray persisting 

 about the vascular elements of 

 the rootlets. 



the tn 



fig. i). 



a 



ugh these "primary" rays 

 well marked signs of in- 

 ion, the broad alternating 

 multiseriate rays are in 



most cases consi 

 their inner ends . 



VI 



the primary multiseriate rays may also show evidences of reduction. 

 However, the disintegration of these rays is most strongly shown 

 usually at some distance from the strands of vascular tissue which 

 supply the rootlets. Stimulating injuries or increased vitality recall 



been retarded. 



lopment 



