56 BOTANICAL GAZETTE [july 



Summary and conclusions 

 The " aggregate' ' ray hypothesis developed by J 



amplified by a numbe 

 an imDortant bearim 



the phylogeny of the angiosperms 

 of the Amentiferae are in all proba 



bility the most primitive living representatives of the phylum. 



serious 



a . ~~,™~ >> 



OBJECTIONS TO THE AGGREGATE RAY HYPOTHESIS 



i. The phenomenon of chalazogamy, which was considered at 

 first of great phylogenetic value, cannot, in view of later investiga- 

 tions, be considered a reliable criterion for determining the phylo- 

 genetic position of plants. 



2. The occurrence of so-called " aggregate " rays in the Tertiary 

 does not appear to be significant, since "multiseriate" rays, which 

 are considered to be a comparatively recent adaptation to the ad- 

 vent of a severe winter season and the consequent acquirement 



middle 



dicotyledons. 



3- K 



com 



for the 



assimilates descending from 



angiosperms in the warmer times of the Mesozoic and 



placed by "multiseriate 



multi 



rays well developed in families which have li\ 

 ments since ancient times. 



4. The "aggregate" ray, which is com 



characterizes the obviously reduced xerophytic Casuarinaceae, 

 and the temperate families Betulaceae, Fagaceae. and Ericaceae. 



5. The "aggregate" ray hypothesis does not account for the 

 development of "secondary" multiseriate rays nor for the origin of 

 wide rays in the root. 



6. The seedling evidence which has been advanced in favor of 



the origin of wide rays from 6 



inv 



dated by the occurrence of wide multiseriate rays in seedlings < 

 oaks, and also in such supposedly conservative regions in th 

 genus as the node. root, renroductive axis; and first annual ring. 



