Alfred Russel Wallace 



mountains. Now, if there is one thing more clear than 

 another it is that Madagascar has been separated from 

 Africa since the Miocene (probably the early Miocene) 

 epoch. These plants must therefore have reached the 

 island either since then, in which case they certainly must 

 have passed through the air for long distances, or at the 

 time of the union. But the Miocene and Eocene periods 

 were certainly warm, and these alpine plants could hardly 

 have migrated over tropical forest lands, while it is very 

 improbable that if they had been isolated at so remote a 

 period, exposed to such distinct climatal and organic en- 

 vironments as in Madagascar and Abyssinia, they would 

 have in both places retained their specific characters un- 

 changed. The presumption is, therefore, that they are 

 comparatively recent immigrants, and if so must have 

 passed across the sea from mountain to mountain, for the 

 richness and speciality of the Madagascar forest vegetation 

 render it certain that no recent glacial epoch has seriously 

 affected that island. 



Hoping that you are in good health, and wishing you 

 the compliments of the season, I remain yours very faith- 



^^l^y> Alfred K. Wallace. 



Down, BecJcenham, Kent. January 2, 1881. 



My dear Wallace, — The case which you give is a very 

 striking one, and I had overlooked it in Nature.^ But I 

 remain as great a heretic as ever. Any supposition seems 

 to me more probable than that the seeds of plants should 

 have been blown from the mountains of Abyssinia or other 

 central mountains of Africa to the mountains of Mada- 

 gascar. It seems to me almost infinitely more probable 



1 ** Nature, December 9, 1880. The substance of this article by Mr. Baker, 

 of Kew, is given in ' More Letters/ vol. iii. 25, in a footnote." — " My Life," 

 ii. 13. 



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