170 The Philippine Journal of Science 



than that of Ceylon in plants whose existence is not so directly 

 menaced by agriculture, will not operate likewise in Ceylon, as 

 the increase of population and the intensification of the use of 

 land brings Ceylon to the point that Java has already reached? 

 Surely, on any well kept plantation in Ceylon, many species 

 once locally common have disappeared. As plantations become 

 more numerous and more extensive and cultivation becomes 

 more intensive, increased rarity and eventual extermination 

 of species, once thriving where agriculture now becomes active, 

 is altogether inevitable. In a sense, this kind of extermination 

 exhibits artificial selection; but artificial selection is never any- 

 thing but a particular phase of the general process at first 

 distinguished as natural selection. Artificial selection is simply 

 selection in which the will of man is intentionally or incidentally 

 the determining factor. 



The validity of the doctrine of natural selection would not be 

 essentially placed in question by the fact that plants are not 

 dying out in Ceylon, even if this were established, unless there 

 were furnished reasons to believe that plants do not die out in 

 general and have not died out in general. That they have died 

 out, everybody knows. Otherwise, where are now the whole 

 groups that, as fossils, we know each year better, which once 

 bridged the gaps between the Pteridophytes of Devonian time 

 and the seed plants? Some good palaeophytogists may tell us 

 how many extinct plants are known this year, but not how many 

 we may know a year or so later. Plants grow rare also, as we 

 know from evidence of the same kind. Sequoia, Taxodium, 

 Glyptostrobus, Torreya, and Cephalotaxus were once genera of 

 very wide geographical range. The Cretaceous or Miocene 

 botanists would have rated these perhaps as very common. 

 With the passage of time, they have become very rare. Matonia 

 represents a group of ferns which for ages was probably world- 

 wide in distribution. It is now known from at least five moun- 

 tain tops in the Malay Peninsula, Borneo, Sumatra, and Amboina. 

 The dying out of species must be usually a very slow perfor- 

 mance, and one that might easily escape attention. We know, 

 though, that.it has gone on in geologic time, in early human time 

 (otherwise, where are the wild forms of our common grains?), 

 that it has gone on in recent historic times, in various localities 

 in England, Java, and elsewhere, and it may well be suspected 

 that, at least as agriculture develops in Ceylon, the same process 

 takes place there. However, even if Ceylon conditions are 

 peculiar in this respect, it would be hard to show that natural 

 selection or its failure is responsible for the peculiarity. 



