302 Proceedings Port. Soc. Nat. Hist. 



elements of the flora of northeastern America. The g:i*eatest 

 amount of evidence, however, seems to be in favor of the 

 theories outlined above, which are accepted by the majority 

 of biologists, both botanists and zoologists. Among the dis- 

 senters from this view-point may be mentioned ScharfiF. In 

 his "Origin of Life in America"' he advances the theory that 

 the pre-glacial flora was not driven south by the advance of 

 the ice but survived the Glacial Period in temperate islands 

 in Labrador and Greenland which escaped glaciation, from 

 which areas it has since spread to its present limits. The 

 southern flora, on the other hand, according to Scharff. sur- 

 vived the Ice Age on the now submerged land bridge which 

 extended from Xew Jersey to Cape Cod and ISTewfoundland 

 and was likewise unaffected by the glaciers. 



There are differences of opinion on other points as well. 

 In referring to the presence of arctic-alpine species on the 

 summit of Mt. Marcy in the Adirondacks, Bray^ disclaims 

 the theory that they are relic types, stating that it is not 

 necessary to assume that the arctic-alpine flora of the high 

 mountains was established at a remote period such as the 

 close of the Glacial Period, "since factors at present operative 

 might account for the carrying of such species to any habitat 

 suited to them.''' 



The geographic aflinities of individual species also afford 

 opportunities for differences of opinion. In general Corema 

 Conradii and Schizaea pusilla (to cite examples) are con- 

 sidered as southern coastal plain types which have pushed 

 north. Stone, however, in his "Flora of Southern New 

 Jersey"' classes them as boreal species which have been driven 

 south. 



1. Scharff. Distributicn and Origin of Life in America. New York. 



1912. 



2. Bray. 1. c. pages 79-80. 



3. Stone. The Plants of Southern New Jersey. Report of N. J. 



State Museum, 1911: 25-828. 



