294 CREATION BY LAW. 



can consist, and in the Fan-tail 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 be- 

 tween species and species in a state of nature, since 

 the differences which we do produce are often com- 

 parable 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 va- 

 riability 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 modifi- 

 cations have equally definite and very similar limits. 



Objection to the Argument from Classification. 



To another of this writer's . objections that by Pro- 

 fessor Thomson's calculations the sun can only have 



