82 Capt. F. W. Hutton on the Origin of the 



Wallace, who is the latest exponent of this view, says that 

 the " causes [which produced the continuous current of vege- 

 tation from north to south] were the repeated changes of 

 climate, which, during all geological time, appear to have 

 occurred in both hemispheres, culminating at rare intervals 

 in glacial epochs, and which have been shown to depend 

 upon changes of eccentricity of the earth's orbit and the 

 occurrence of summer or winter in aphelion, in conjunction 

 with the slower and more irregular changes of geographical 

 conditions ; these combined causes acting chiefly through 

 the agency of heat-bearing oceanic currents and of snow-and- 

 ice-collecting highlands " *. 



An inhabitant of the southern hemisphere may well ask in 

 surprise, " Where is the evidence for this comprehensive 

 statement ? " And Mr. Wallace himself, in the ninth chap- 

 ter of his book, argues lucidly in favour of there having been 

 no changes of any importance in the climate of the northern 

 hemisphere between the Triassic and Pleistocene periods. All 

 the information we obtain from Mr. Wallace is the follow- 

 ing : — « That there was such a greater accumulation of ice [in 

 the southern hemisphere] is shown by the traces of ancient 

 glaciers in the Southern Andes and in New Zealand, and also, 

 according to several writers, in South Africa, and the 

 indications in all these localities point to a period so recent 

 that it must almost certainly have been contemporaneous 

 with the glacial period of the northern hemisphere " f. And 

 further on he says, " We may further assume that what we 

 know took place within the Arctic circle also took place in the 

 Antarctic — that is, that there have been alternations of climate 

 during which some portion of what are now ice-clad lands 

 became able to support a considerable amount of vegetation " \. 

 This is all I can find in Mr. Wallace's book, and it must be 

 allowed that it is very unsatisfactory. Let us therefore try 

 to estimate fairly what the evidence really is. 



The only evidences in the south of former temperatures 

 higher than at present are : — (1) The Miocene fauna which I 

 discussed in my former address, and (2) The fossil trees of 

 Kerguelen's Land and theCrozet Islands, which must once have 

 formed part of a luxuriant forest. But at the present time 

 Fuegia, which is considerably south of Kerguelen's Land, 

 supports luxuriant forests §, and so also might the Crozet 



* ' Island Life/ p. 484. t Loe. cit. p. 157. 



I Loc. cif. p. 490. 



§ Dr. Coppinger says that in tie museum of Santiago therein a section 



