ON THE SUPPOSED TERTIARY ANTARCTIC CONTINENT. 



By Sir William Turner Thiselton-Dyer, D.Sc, LL.D., F.R.S. 



Looking back, as I have recently had occasion to do, on the history of the 

 gradual development during the last century of a rational theory of the distri- 

 bution of life on the surface of the earth, it can hardly be contested that the 

 germinal ideas have had their origin in the old world. But it must also be ad- 

 mitted — and it is not inappropriate on this occasion to recall the fact — that 

 the ultimate shape they have assumed is largely due to a great American man of 

 science. 



Linnaeus laid it down that the individuals of a species must have had a common 

 parentage. But a great difficulty arose in applying this principle when it was 

 seen that individuals of the same species frequently occur in widely dissevered 

 areas. One solution was to reject the principle and to assume, as has been done 

 as lately as by Agassiz, that species have had "multiple origins." 



Another solution first proposed by Forbes and adopted by Lyell and Hooker 



was to assume "the destruction of considerable areas of land 



Writers 



geographical distribution now occupied themselves, to use Darwin's words, " in 

 sinking imaginary continents in a quite reckless manner" and in constructing 

 land bridges in every convenient direction. They were brought back to the 

 stern reality of fact when Dana in his Manual of Geology first made the unex- 



pected statement 



(( 



The continents and oceans had their general outline 



form defined in earliest time 

 From this view Darwin, su 



deviated 



pported as he was by his own reflections 



Writing to Hooker in 1856 he said, "you cannot imagine how earnestly 



I wish I could swallow continental extension, but I cannot" (Life and Letters 

 II, 81). 



In applying Dana's principle to the great northern and southern regions of 

 the world's vegetation first indicated by Hooker, botanists may admit that as 

 regards the former, known means of physical transport may afford a sufficient 

 planation, but it must be conceded that as regards the latter they are quite 



inadequate 



The northern temperate flora occupies large continuous surfaces 



Australia, South Africa 



the southern is distributed over widely dissevered 



South America. Yet each with its own characteristic facies contains common ele- 

 ments, the significance of which it is impossible to ignore, pointing as they do 

 to a common origin. A few examples must suffice. Few families in the vegetable 



kingd 



om 



more sharply defined than Proteaceoe: thev have their headquarters 



m Australia and South Africa, Banksia for example in the one and Protea in the 

 other may be taken as examples ; they are more feebly represented by the lovely 



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