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, Taxoclium, 
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. 
