38 BOTANICAL GAZETTE [july 



Especially significant are two collateral lines of evidence which 

 have played an important part in amplifying the original hypothe- 

 sis. The first of these is concerned with the connection between 



certain "aggregate" and "compound" rays and the traces of 



leaves, a phenomenon which is said to indicate conclusively that 

 "aggregate" and "compound" rays were "built up" for pur- 

 poses of storing the assimilates descending from the large per- 

 sistent leaves of mesozoic angiosperms. The second line of 



evidence 



formed to the mature 



stems of certain Ericales, Fagales, and Casuarinaceae. This 



a 



uence has been interpreted 

 type of ray originated from 



"aggregate" or "com 



Objections to the "aggregate" ray hypothesis 



In endeavoring to trace certain steps of the evolutionary history 

 of the so-called "aggregate" and "compound" rays in the Fagales, 

 one of the writers (Bailey *ii) discovered indications of reduction 

 in Castanea and Alnus. Additional investigations ('12) of these 

 genera, and of Castanopsis, Ostrya, and Carpinus revealed much 

 evidence for believing that the "aggregate" and "compound" 

 rays have disappeared or are in the process of disappearing from 

 living species of these genera. Furthermore, Groom ('ii) has sug- 

 gested that the small rays of Quercus may have originated by the 

 disintegration of primitive wide multiseriate rays. It is some- 

 what difficult to harmonize completely these observations with the 

 general trend of the investigations upon "wide" rays, since they 

 introduce the possibility that the congeries of small rays (the so- 

 called "aggregate" rays) may be in every case stages in the "break- 

 ing down" rather than in the "building up" of wide rays. Thi 

 fact is particularly significant when we consider that the "aggregate " 

 ray hypothesis derives much of its support from the theory that the 

 chalazogamic Amentiferae are in all probability the most primitive 

 living angiosperms, for many botanists, from comparative studies 

 of sporophytes and gametophytes, consider that these angiosperms 

 with unisexual flowers are reduced rather than truly primitive. 



