40 BOTANICAL GAZETTE [july 



subgenus Erythrobalanus , since in the latter the " aggregation " 

 and " fusion" of rays begins much earlier. Similarly, the "live" 

 or "evergreen" oaks are regarded as more primitive than either 

 of these types, since they possess even in the mature wood "aggre- 

 gate" tissue from which the separating fibers have not been entirely 

 eliminated. 



The writers have recently examined seedlings of different 

 species of the Fagales, and have found phenomena that are appar- 

 ently of considerable interest. Especially significant are the effects 

 of different degrees of vigor upon the development of ray struc- 

 tures in seedling plants. Suppressed, slow-growing, feeble plants 

 are characterized in many cases by the retarded development of 

 large rays. In fact, the effect of stunted growth may be so 

 strongly marked that only uniseriate rays are formed in stems 

 30-50 years old. On the other hand, in plants with large, vigorous, 

 well nourished growing points the development of large rays is 

 often accelerated. Vigorous specimens of certain oaks, e.g., Quercus 

 rubra L., may even possess wide rays (so-called compound or com- 

 pletely parenchymatous rays) in the first formed portion of the 

 seedling stem (figs. 3 and 13). In the ontogeny of these rays, as in 



those of Fagus grandifolia Ehrh. and F. sylvatica L 



are no putative stages of "aggregation" and fusion. 



It is somewhat difficult to exDlain satisfactor 



1) there 



the facts of 



anatomy 



mi 



multiseriate typ 



in 



from 



rays. 



The seedling or young plant has been shown in a number of 

 cases to retain characters that are in all probability ancestral, but 

 these phenomena have been interpreted differently by different 

 investigators. Hill and DeFraine and others maintain that 

 the seedling is very sensitive to changes in its internal or external 

 environment and therefore of little or no value for phylogenetic 

 purposes. Primitive structures persist only where they are ol 

 functional importance in the young plant. In opposition to this 



