98 OBJECTIONS TO THE HYPOTHESIS [pt. i 



of the latter, then the same thing is going on in the genera that 

 possess none, i.e. they are dying out without competition, and 

 at the same rate, a remarkable fact. If endemics are local species 

 developed in response to local conditions, then it is very remark- 

 able that in the genera where they have not been able to kill out 

 the wides, the latter should occupy the largest range (cf. map 

 of Ranunculus, p. 156, or almost any other genus of Ceylon or 

 New Zealand that possesses wides). 



What the explanation of "swamping" may be is not as yet 

 clear, though it seems probable that it goes to some extent with 

 the mere age of a genus, especially if of woody habit. But its 

 existence does not in any way prejudice the vahdity of Age 

 and Area as an explanation of distribution, for the presence 

 or absence of wides makes no difference to the behaviour of 

 genera. 



Another objection is (29) that much detailed work is being 

 done in splitting up large and wide-ranging Linnean species into 

 micro-species, and that this will destroy the value of my work, 

 as I have dealt only with Linnean species. This, translated into 

 terms of the figures which have been given in Chapters vi-viii, 

 means that species are being removed from the column of 

 "wides" into that of endemics, and perhaps \isually to near the 

 bottom of this. The result will not be to undermine my work, 

 but rather to strengthen it. As one of our leading ecologists says 

 in a letter to me. and underlines, "this will be strongly in favour 

 of your Age and Area hypothesis." 



It is also objected (30) that species with wide distribution are 

 usually found in an early stage of the plant succession. This is 

 practically the same as the old axiom of the systematists "sim- 

 plicity of type goes with increase of area." Later species in a 

 country that is undergoing change of climate will tend to be 

 adapted to more strictly local conditions, and their spread will 

 therefore be hindered by ecological boundaries. But it is to 

 some extent a single-species objection. 



The general objection, never perhaps expressed in so many 

 words, but running through a number of those actually given, 

 (31) that Age and Area does not agree with ecological results, 

 is largely answered in what has been said above. Age and Area 

 works over much longer periods than does local ecology, and 

 must not be applied to single species, and it must not be for- 

 gotten that it is not a mere unsupported hypothesis, with no 



