44 THE PLANT WORLD. 



by way of the Antarctic Continent at the close of the Cretaceous ; 

 the invasion of the sea resulting in isolation of the six great land 

 masses of the globe in the Eocene, favoring the development of 

 distinct faunas and floras; subsequent emergence with invasion 

 of new forms from Asia into Xorth America and Europe contin- 

 uing through the Miocene ; great elevation during the Pliocene, 

 again permitting exchange of forms in l)otli directions between 

 Xorth and South America ; and simultaneous glaciation in both 

 hemispheres in the Pleistocene, with its necessary results, are thc^ 

 salient features of interest to students of distribution, 



Guppy's Observations of a Naturalist in the Pacific (Mac- 

 niillan & Co., 1906) contains some interesting experiments in 

 regard to seed-buoyancy, which go to show that a large percentage 

 of the coast plants of a Pacific island might have been brought 

 to its shores by ocean currents, notwithstanding certain barriers 

 which render this process, in many cases, quite inadequate. The 

 movements of birds as an effective agency is emphasized, and the 

 problem of endemic genera has some light thrown upon it, if the 

 author's views regarding submergence and uplift of various 

 groups of Pacific islands are to be accepted. 



It is of interest to note that the author just cited has no 

 faith in acquired adaptations. A plant that is fitted for a cer- 

 tain habitat lives in that habitat if it "'gets there," but does not 

 become adapted to it. Similar views are now frequently put 

 forth by others. Thus Piper — Flora of the state of Washington 

 — '"Following the retreat of the ice, the areas that then became 

 fitted to support an upper Sonoran fiora could have become in- 

 habited either by the northward extension of already adapted 

 plants, or by the gradual modification of species of a colder zone, 

 or by both. The evidence indicates the first method to have 

 been the most potent." It becomes increasingly evident that the 

 origin of adaptations is still a subject for active investigation. 



Dr. J. W. Harshberger has recently been made assistant 

 professor of botanv of the Universitv of Pennsvlvania, a well 



