460 TROPICAL NATURE 



botanists, farmers, gardeners, sporting -men, pigeon -fanciers, 

 travellers, and any one who could possibly afford direct per- 

 sonal information on any of the matters he was investigating. 

 Then came his own observation and experiment, to fill up gaps, 

 to settle doubtful points, or to determine questions the import- 

 ance of inquiring into which no one had ever suspected ; and 

 lastly, there was the power of arrangement and comparison, 

 the originality and depth of thought, which drew out from this 

 vast mass of heterogeneous materials conclusions of the highest 

 value as bearing on the question of the possible change of 

 species, and the means by which it had been brought about. 



In order to determine the nature and amount of the varia- 

 bility of domestic productions, he prepared skeletons of all 

 the more important breeds of rabbits, pigeons, fowls, and 

 ducks, as well as of the wild races from which they are 

 known to have been produced, and showed, both by measure- 

 ments and by accurate drawings, that not only superficial 

 characters, but almost every part of the bony structure 

 varied to such an amount as usually characterises very dis- 

 tinct species or even distinct genera of wild animals. Another 

 set of experiments was made by crossing the different breeds 

 of pigeons and fowls which were most completely unlike the 

 wild race, with the result that in many cases the offspring 

 were more like the wild ancestor than either of the parents. 

 These experiments, supported by a mass of facts observed by 

 other persons, served to establish the principle of the tend- 

 ency of crosses to revert to the ancestral form ; and this 

 principle enabled him to explain the interesting fact of the 

 frequent appearance of stripes on mules, and occasionally on 

 dun-coloured horses, on the hypothesis, supported by a mass 

 of collateral evidence, that the common ancestor of the horse, 

 ass, and zebra tribe was a partially striped and dun-coloured 

 animal. 



A number of very important conclusions were deduced 

 from the facts presented by domesticated animals and plants, 

 a few of which may be here referred to. For example, it 

 was proved that the parts most selected or which had already 

 most varied as the tail in fan-tailed pigeons, which has more 

 tail-feathers than any one of the 8000 different kinds of 

 living birds were most subject to further variation; and 



