68 ROYAL SOCIETY OF CANADA 



Bringing these results into comparison with the sequence estab- 

 lished by EichleT on a more general morphological basis, it will be 

 seen that there is a very general agreement, perhaps quite as much 

 as could be expected to result from an examination of relationships 

 from such diverse points of view. If further, we attempt to express 

 these results by a curve, it will appear somewhat more clearly how 

 certain genera fall into groups which do not necessarily imply genetic 

 relationship, but rather the fact that similar positions in development 

 have been attained by different genera quite independently, though 

 along similar lines. 



The precise significance of these facts cannot be determined from 

 the limited amount of material at present available for that purpose, 

 nor would it be wise to attempt the formulation of any final conclu- 

 sions, but it does seem appropriate to point out that in considering 

 any data in extension of the present studies, a correct interpretation 

 of all the facts will be gained most satisfactorily in the light of tne 

 Mutation Theory which De Vries has so carefully elaborated. As 

 leading to this end, the present facts suggest that 



1. The various sporadic characters are tendencies toward higher phases of 



development which do not become fully expressed, and they there- 

 fore represent imperfect parallelisms along lines of development 

 which attain full expression in other genera. 



2. The occurrence of resin passages in Abies cannot be traced, at present, 



beyond existing species, and such structures afford no evidence, as 

 yet, of phylogenetic value. 



3. Sequoia represents a transitional group having gi strong tendency to varia- 



tion, with respect to the development of resin canals and fusiform 

 rays in succession to the simple resin cells and uniseriate rays. 



4. Sequoia gigantes represents the more stable member of the genus, devia- 



tions being most marked among existing species, in S. sempervirens. 

 5 Sequoia represents the terminal member of a short side line which passes 

 through Taxodium and gives off further side lines as expressed in the 

 formation of fusiform rays in S. burgessii, and imperfect resin pas- 

 sages in S. sempervirens. 



