1914] BAILEY & SINKOTT—PHYLOGENY OF ANGIOSPERMS 41 



are the views of Jeffrey, who considers that Haeckel's doctrine 

 of recapitulation is of "universal validity," as invariably operative 

 as the laws of chemistry, physics, and the other cognate sciences. 

 A more conservative working hypothesis which combines elements 

 from each of these antagonistic extremes is held by other biologists, 

 who believe that there are categories of predominantly conservative 

 and of predominantly variable characters, just as there are organs 

 or regions of the plant that are more retentive of primitive char- 

 acters than others. The mere fact that certain ontogenetic char- 

 acters have been found to be extremely inconstant and sensitive 

 to physiological conditions does not necessarily invalidate the 

 doctrine of recapitulation. Nor does the fact that the young plant 

 has been shown in certain cases to retain ancestral features indi- 

 cate that every seedling character is of phylogenetic value. The 

 seedling may display a strong tendency toward conservatism and 

 still be subject to environmental influences, just as the behavior 

 of a falling body may be influenced by other forces than that of 

 gravity. However, the fact that any character in the young plant 

 may be subject to modification by physiological changes makes it 

 difficult in many cases to distinguish palingenetic from cenogenetic 

 features. Phylogenetic conclusions drawn from the study of the 

 structure of seedlings are not conclusive unless substantiated by 

 reliable corroborative evidence. 



somewhat paradoxical behavior of wide 



stem 



to be conservative and retentive of ancestral characters has an 



» 



important bearing on the nroblem under discussion. 



THE ROOT 



In a recent paper Jeffrey (*ia) makes these comments upon the 

 conservatism of the root: 



There are organs of the plant, for example, even more strongly retentive 

 of ancestral characters than the seedling stem. Perhaps the most conservative 

 organ is the root, which varies so little in its fundamental organization through- 

 out the vascular plants that one formula will represent the organization of all 



roots. 



Fagus grandifolia and F. sylvatica (fig, 2) possess 

 formed secondary xvlem multiseriate rays which 



