VII 
CREATION BY LAW 
161 
cannot be further developed in the same direction. Variation 
seems to have reached its limits in these birds. But so it has 
in nature. The fantail has not only more tail feathers than 
any of the three hundred and sixty existing species of pigeons, 
but more than any of the ten thousand known species of birds. 
There is, of course, some limit to the number of feathers of 
which a tail useful for flight can consist, and in the fantail we 
have probably reached that limit. Many birds have the 
oesophagus or the skin of the neck more or less dilatable, but 
in no known bird is it so dilatable as in the pouter pigeon. 
Here again the possible limit, compatible with a healthy 
existence, has probably been reached. In like manner the 
differences in the size and form of the beak in the various 
breeds of the domestic pigeon is greater than that between 
the extreme forms of beak in the various genera and sub- 
families of the whole pigeon tribe. From these facts, and many 
others of the same nature, we may fairly infer that if rigid 
selection were applied to any organ, we could in a comparatively 
short time produce a much greater amount of change than 
that which occurs between species and species in a state of 
nature, since the differences which we do produce are often 
comparable with those which exist between distinct genera or 
distinct families. The facts adduced by the writer of the 
article referred to, of the definite limits to variability in certain 
directions in domesticated animals, are, therefore, no objection 
whatever to the view that all the modifications which exist in 
nature have been produced by the accumulation, by natural 
selection, of small and useful variations, since those very 
modifications have equally definite and very similar limits. 
Objection to the Argument from Classification 
To another of this writer’s objections — that by Professor 
Thomson’s calculations the sun can only have existed in a 
solid state 500,000,000 of years, and that therefore time 
would not suffice for the slow process of development of all 
living organisms — it is hardly necessary to reply, as it cannot 
be seriously contended, even if this calculation has claims to 
approximate accuracy, that the process of change and develop- 
ment may not have been sufficiently rapid to have occurred 
within that period. His objection to the classification argu 
M 
