i/6 



Dr. Britton was one of the prime movers in the framing of the 

 so-called "Rochester" and "American" codes of botanical nomen- 

 clature, which emphasized the priority principle in the selection of 

 the valid Latin names for genera and species of plants. The adop- 

 tion of these principles by Britton in the "Illustrated Flora," the 

 "Manual," etc. ; by Small in his "Flora of the Southeastern United 

 States" ; by Rydberg in his "Flora of the Rocky Mountains" ; and 

 by various other contributors to the literature of systematic botany, 

 led to a wide use of names that, in many cases, were different from 

 those that had been made familiar by the earlier American manuals. 

 Attempts to have the "American Code" adopted in its essential 

 entirety by all of the botanical world have failed, yet many of its 

 distinctive features are recognizable in the latest revision of the 

 "International Rules of Botanical Nomenclature." Much of the 

 diversity in nomenclature that still persists is due to differing ideas 

 as to generic and specific limits. Genera and species being essenti- 

 ally subjective concepts rather than objective realities, their mate- 

 rial content does not seem to be subject to successful legislation by 

 botanical congresses. 



In his limitation of species, Doctor Britton was, on the whole, 

 rather "conservative," but in defining genera his tendency to "split" 

 rather than to "lump" is perhaps especially notable in the hand- 

 some Britton and Rose four-volume work on "The Cactaceae" 

 published by the Carnegie Institution of Washington in 1919-23. 

 Britton and Rose recognize 124 genera and about 1,237 species. A 

 third of a century earlier, Dr. K. Schumann, in his treatment of 

 the Cactaceae in Engler and Prantl, "Die naturlichen Pflanzen- 

 familien" recognized 20 genera and about 775 species. While the 

 increase of genera from 20 to 124 was largely of the "splitting" 

 or "segregating" type, in conformity with the general trend of 

 biological practice, it is an indisputable fact that Britton and Rose 

 had at their disposal vastly more material than was available to 

 any of their predecessors, and the increase in the number of recog- 

 nized species from yy^ to [,237 represented a notable advance in 

 actual knowledge of the living forms exhibited by the Cactus 

 Family. Tin's elaborate monograph doubtless represents the 

 climax of Doctor Britton's contributions to scientific literature. It 

 has established a new datum line from which future investigations 

 ot the Cactaceae must proceed. In a letter received at The Xew 



