192 H. B. GUPPY, F.R.S.E., ON PLANT-DISTRIBUTIOX 



been received Ly most botanists, and by many its connection 

 with physical causes has been either tacitly assumed or directly 

 implied. The differentiation of the plant and of its conditions 

 have ever gone on together. As indicating the general position, 

 I will here quote from the address of Professor F. W. Oliver to 

 the Botanical Section at the last meeting of the British 

 Association. . . "It is generally conceded (he said) that the 

 primitive vegetation arose in the M'aters, and that with the 

 parting of the waters and the emerging of land and continents 

 this primitive stock of plants was sufficiently plastic to take 

 advantage of the new conditions, throwing up successive hordes 

 which affected a footing on the land, and in time peopled the 

 whole earth with forms adapted to the varying habitats and 

 climates as they differentiated." 



Nature would thus seem all attuned, but there is a rift within 

 the lute and a jarring note strikes on our ears. The sudden 

 ^ippearance of the Angiosperms in the Lower Cietaceous period 

 without a warning note interrupts the harmony of nature's 

 processes. We can, it is true, detect the same principles at 

 work both before and since the Chalk, yet the break remains. 

 But little can be said here of the indications of Palaeozoic times, 

 though as far as my data go, they seem clear enough. It 

 •appears to be generally recognised that during the early part of 

 the Carboniferous epoch uniformity of climate and of vegetation 

 prevailed over the world.* With the Coal Measures, to employ 

 the w^ords of Dr. Scott, "a differentiation of floral regions 

 began," and we find at the close of the Palaeozoic eras, that the 

 world's plants, though everywhere constituting, as Mr. Newell 

 Arber observes, another great epoch in the history of the 

 vegetable kingdom, had grouped themselves into two great 

 iloras, the Northern and the Southern. 



It was not, however, until alter the sudden appearance of the 

 Angiosperms in the Lower Cietaceous period that the ages of 

 world-wide floras began to pass away, and plants came to be 

 " distributed more markedly according to geographical provinces 

 and in climatic zones. ' Through the Tertiary period the process 

 •of diffeientiation of floras was continued ; and accordingly we 

 lind that the iarther we go back in that period from the 



* See the article on Pjiljeobotany in vol. 31, EiwycL Bn't., p. 421 

 (Dr. Scott) and p. 422 (Mr. Sowaid) ; also Mr. Seward's address {Brit. 

 Assoc. 1903) ; also l*rof. llidl's CodljieUh of Great Britain^ edition, 

 1905 ; also Mr. Newell Arhei's Ctttaloijm of the Fom'i Blaiits of the 

 'iJ tossopteris Flora in the British Museum^ lfK>5 



