136 WILLIS : THE FLORAS OF 



Malay Peninsula, but until their floras have been more com- 

 pletely worked out it is hardly possible to give details. 



The first question thajt will occur to every one is, Why do not 

 the hills of, say. Great Britain, shoAV similar phenomena ? 

 Is it that evolution goes on more easOy or rapidly in the 

 tropics, or is it that the hills in Ceylon, &c., are older, or that 

 distribution is less easy in a forest-covered country 1 In the 

 great ranges of the Alps, Pyrenees, &c., there are a good many 

 local endemic forms, but probably the two latter, at any rate, 

 of the causes mentioned, have prevented their occurrence in 

 Britain. 



The next question will be, are not these isolated species to be 

 regarded as survivals upon the hill tops of species that may at 

 some former period have lived lower down ? We have no 

 evidence, so far as I am aware, that the glacial period produced 

 much e£Eect so near to the equator ; but apart from that, why 

 should there be different survivals upon nearly every hill, 

 while the bulk of the flora is the same, showing that the 

 composition of the flora of the plains — assuming that the hill 

 flora did ascend from below — was much alike, all over the wet 

 country at any rate ? If the hills were far apart, and if there 

 were any evidence to show that the different parts of the 

 plains — other than the wet and the dry — ever differed in 

 climate, we might consider this objection as sound, but it is 

 impossible to so regard it in the actual state of affairs. 



Now, if isolation alone is to effect specific difference, the 

 general evidence is necessarily against selection of infinitesimal 

 differences from the adaptation point of view. Why should 

 some species range over the whole of the mountain tops, while 

 others are confined to one ? Why should there be a gi:eat 

 many Eugenias each confined to one hill top, while E. suhavenis, 

 E. assimilis, E. mahceoides, &c., though endemic to Ceylon, 

 range over the bulk of the higher mountains ? The common - 

 sense view is that these plants are not specially adapted for 

 their situations, but that the commoner or more widely spread 

 species are better suited to mountain tops generally, or were 

 evolved sooner and have had time to spread more widely. 



Or, again, look at the chmatic range in which the bulk of the 

 species found in Ceylon can survive and prosper, and it will be 



