Septembek 11, 1914] 



SCIENCE 



361 



plan of land-elevations on the earth is ap- 

 proximately tetrahedral; and it is, I be- 

 lieve, in line with the views of those who 

 are best informed on antarctic geography 

 and geology, as studied from the land 

 itself. It may be hoped that further ant- 

 arctic discovery may bring fresh facts to 

 bear upon this question, for it is to the 

 positive data acquired from study of the 

 earth's crust that we must look, rather than 

 to the exigencies of botanists and zoolo- 

 gists, for its final solution. 



But tlie hypothesis of an Antarctic land- 

 connection has been held open to doubt in 

 various quarters. As Sir Wm. Thiselton 

 Dyer has recently pointed out, Darwin 

 himself dissented, though regretfully, from 

 the sinking of imaginary continents in a 

 quite reckless manner, and from the con- 

 struction of land-bridges in every conveni- 

 ent direction. From the geological side 

 Dana laid down the positive proposition 

 that the continents and oceans had their 

 general outline and form defined in earliest 

 time. Sir John Murray, whose recent 

 death we so deeply deplore, was an un- 

 deniable authority as to the ocean-floor. 

 He wrote quite recently with regard to 

 Gondwana-land, that "the study of ocean- 

 depths and ocean-deposits does not seem 

 in any way to support the view that con- 

 tinental land has disappeared beneath the 

 floor of the ocean in the manner indi- 

 cated." He suggested that the present 

 distribution of organisms is better inter- 

 preted by the North Polar theory of origin. 

 The "continuous current of vegetation" 

 southward at the present time was recog- 

 nized by Hooker himself, and definite 

 streams of northern forms have been traced 

 by him extending even to Australia and 

 Tasmania. This might account for much 

 in present-day distribution; though it 

 seems doubtful whether it would fully ex- 

 plain the extraordinary distribution of Ant- 



arctic plants. The problem must for the 

 present remain an open one. 



This whole question, however, has a con- 

 nection with the stiU wider difficulty of the 

 existence within the polar area of ancient 

 floras. In the north the fossils are even of 

 sub-tropical character. Coal has been 

 found in lands with a five months' night. 

 How did such plants fare if the seasonal 

 conditions were at all like the present? 

 To explain this it would be a physiological 

 necessity to assume either an entirely dif- 

 ferent climatal condition in those regions 

 from that of the present time; or, as has 

 been suggested, some shifting or creeping 

 of the earth's crust itself. These are, how- 

 ever, questions which we can not under- 

 take to discuss with effect in the Botanical 

 Section. We must not do more than recog- 

 nize that an unsolved difficulty exists. 



We pass now from Hooker's great work 

 to the last of the classical series, viz., the 

 "Flora Australiensis" of Bentham and 

 Baron Ferdinand von Miiller. It is em- 

 bodied in seven volumes, and was com- 

 pleted in 1878. Bentham, while assenting 

 in his "concluding preface" to the prin- 

 ciples laid down by Hooker in the Tasman- 

 ian flora, recognized as the chief com- 

 ponent part of the present flora of 

 Australia the indigenous genera and species, 

 originated or differentiated in Australia, 

 which never spread far out of it. Sec- 

 ondly, an Indo- Australian flora showing an 

 ancient connection between Australia and 

 the lands lying to the north. It is repre- 

 sented especially in tropical and sub- 

 tropical east Queensland. Then there is 

 the mountain flora common to New Zea- 

 land, and extending generally to the south- 

 em extra-tropical and mountain regions, 

 while other constituents are ubiquitous 

 maritime plants, and those which have been 

 introduced since the European coloniza- 

 tion. But the most remarkable, as they are 



