50 CONTACTS WITH DARWINISM III [ch. v 



Ranunculus sagittifolius, confined to the high mountain region 

 about Nuwara Eliya (Ceylon), differs widely from the only other 

 Ceylon buttercup, R. Wallichianus (South Indian also), which 

 occurs side by side with it, though in drier and sunnier places, 

 but is closely allied to R. reniformis of the mountains of the 

 western Indian peninsula, differing mainly in the petals, which 

 are five in the Ceylon species, twelve to fifteen in the Indian one. 

 . . .Are we to suppose the conditions of life so different in the 

 Ceylon and Indian mountains that a five-petalled flower will suit 

 the one, a twelve-petalled the other? Or how is the one to pass 

 into the other, or both to arise from a common ancestor, except 

 by discontinuous variation? Can it be supposed that the simple 

 obovate-lanceolate leaf of Acrotrema intermedium fits it for the 

 Kitulgala district (Ceylon), while the pinnate leaf with linear- 

 lanceolate segments of A. Thwaitesii fits that species for the 

 Dolosbage district, but a few miles away, a trifle higher up, and 

 in a similar climate?. . .A. lyratum, characterised by very long 

 peduncles, is found only on the summit of Nillowekanda, an 

 isolated precipitous rock. . .is it to be supposed that the long 

 peduncles are any advantage . . . ? W^hat advantage can the two 

 ovules of Polyalthia Moonii and P. persicifolia be against the one 

 of the other species? P. rufescens, another species with two ovules, 

 and closely allied to both, occupies the Cochin district of South 

 India, and why should there be three species in so similar a 

 country . . . ? And how did the one form arise from the other, or 

 both arise from a common ancestor, except by mutation? Similar 

 queries might be asked 800 times for the 800 endemics ... in the 

 Ceylon flora. 



The only possible explanation to my mind was that provided 

 by the "parent and child" theory, that parent and child might, 

 and very often did, exist side by side. 



The general principle on which India and Ceylon have been 

 peopled with the many species which they contain would seem to 

 be that one very common species has spread widely, and, so to 

 speak, shed local endemic species at different points, or in other 

 cases that one species has spread, changing at almost every point 

 into a local endemic species, which has again changed on reaching 

 new localities. 



A very good proof for mutation, and indeed for differentiation 

 also, is provided by the work done by Mr G. Udny Yule and the 

 writer upon the statistics of evolution (76). We showed that the 

 evolution of new genera out of old followed with very great close- 

 ness the rule of compound interest. After some time one genus 

 becomes two, and so on. But if genera are formed like this it is 

 hard to believe that they can have been formed by gradual steps, 



