TRANSACTIONS OF SECTION E. 737 



it ever existed, liaviag been the birthplace of that flora ; and there are two 

 reasons for adopting the opposite theory, that the southern flora came from the 

 north temperate zone. Of these, one is the number of northern genera and species 

 (which, from their all inhabiting north-east Europe, I have denominated Scandi- 

 navian),^ that are found in all Antarctic and south temperate regions, the majority 

 of them in Fuegia, the flora of which country is, by means of the Andes, in the 

 most direct communication with the northern one. The other is the fact I have 

 stated above, that the several south temperate floras are more intimately related to 

 those of the countries north of them than they are to one another. 



And this brings me to the latest propounded theoretical application of the laws 

 of geographical distribution. It is that recently advanced by Mr. Thiselton Dyer, 

 in a lecture ' On Plant distribution as a field of Geographical Research' ; - wherein 

 he argues that the floras of all the countries of the globe may be traced back at 

 some time of their history to the northern hemisphere, and that they may be 

 regarded in point of affinity and specialisation as the natural results of the con- 

 ditions to which they must have been subjected during recent geological times, on 

 continents and islands with the configuration of those of our globe. This hypothesis 

 derives its principal support from the fact that many of the most peculiar endemic 

 plants of the south have representatives in the north, some of them living and all 

 of them in a fossil state, whilst the northern endemic forms have not hitherto been 

 found fossil in the southern regions. So that, given time, evolution, continental 

 continuity, changes of climate and elevations of thie land, and all the southern types 

 may be traced back to one region of the globe, and that one palaeontology teaches 

 us is the northern. 



A very similar view has been held and published at the same time bv 

 Count Saporta,^ a most eminent palaeontologist, in a suggestive essay entitled 

 ' L'Ancienne Vegetation Polaire.' Starting from Buff'on's thesis, that the cooling of 

 the globe having been a gradual process, and the Polar regions having cooled first, 

 these must have first become fit for organic life. Count Saporta proceeds to assume 

 that the termination of the azoic period coincided with a cooling of the waters to 

 the point at which coagulation of albumen does not take place, when organic life 

 appeared in the water itself. I have discussed Count Saporta's speculations else- 

 where ; * it is sufficient here to indicate the more important ones as bearing upon 

 distribution. These are that the Polar area was the centre of origination of all 

 the successive phases of vegetation that have appeared on the globe, all being 

 developed in the north ; and that the development of flowering plants was 

 enormously augmented by the introduction during the latter part of the secondary 

 period of flower-feeding insects, which brought about cross-fertilisation. 



It remains to allude briefly to the most important general works on distribu- 

 tion that have appeared since the foundation of this Association. Of these, the 

 two which take the first rank are Professor Alphonse de CandoUe's ' Geographic 

 Botanique,' and Mr. AVallace's ' Geographical Distribution of Animals.' Professor 

 de CandoUe's work'' appeared at a critical period, when the doctrine of evolution 

 with natural selection had onl)' just been announced, and before the great in- 

 fluence of geological and climatal changes on the dispersion of living species had' 

 been fully appreciated ; nevertheless it is a great and truly philosophical work, 

 replete with important facts, discussed with full knowledge, judgment, and scrupu- 



' See Outlines of the Bi.itribution of Arctic Plants, Transactions of tJie Linneaiy 

 Societi/, xxiii. p. 257. Bead June, 1860. 



- Prpcecdinfjs of the lioyal Geographical Sooiett/, xxii. p. 415 (1878). 



' Comptes rendtis of the International Congress of Geographical Science, which^ 

 met in Paris in 1875, but apparently not published till 1877. 



■• Address of the President delivered at the anniversary meeting of the Royal 

 Society of London, November 30, 1878. 



* Professor Alph. De Candolle divides his subject into botanical geography and 

 geographical botany ; the distinction is obvious and sound, biat the two expressions 

 have been so long used and regarded as synonymous, and as embracing both branches, 

 that they cannot now be limited each to one. Perhaps the terms topographies.! 

 botany and geographical botany would prove more acceptable designations 



188L 3 B 



