USES OF A RESEARCH MUSEUM 167 



sentation of specimens of the pure, native stock be properly preserved 

 in our museums, for future comparison. 



I wish here to register an objection to the prevalent idea that ex- 

 perimental methods upon the higher animals under artificially im- 

 posed conditions may be expected to lead invariably to the satisfactory 

 solution of evolutionary problems. I have in mind some experiments 

 recently made upon birds. Certain species were kept captive in en- 

 closures in which a relatively high atmospheric humidity was main- 

 tained. The experimenter found that within the life of an individual, 

 in fact within a few months, successive molts resulted in the plumages 

 of some of the birds becoming darker. Feathers which were normallv 

 marked lightly with black became solid black. The increase of pig- 

 ment throughout the plumage brought about a conspicuous change in 

 the appearances of the birds, as great a difference as one finds between 

 two near-related species under natural conditions, the one occupying 

 an area of arid climate, the other a region of humidity. 



The conclusion from these few experiments, quite generally, but, I 

 feel confident, too hastily, drawn, has been that there may be a " direct 

 influence " of the atmospheric humidity sufficient to bring about the 

 color characters of the different species as we find them under the 

 varying natural conditions; in other words, that it is not a matter of 

 gradual adaptive acquisition subject to inheritance. It is even being 

 maintained widely among biologists that natural selection may have 

 very little to do with the characters of animals as we find them in na- 

 ture. 



I believe that the above experiments, among others carried on in 

 the same way, will, alone, lead to inductions largely inapplicable to 

 animals in the wild. My chief objection is that wild animals brought 

 into confinement at once begin to show irregularities in various* struc- 

 tural respects. This is shown sufficiently by studies upon the skeletons 

 of animals dying in zoological parks, a very large proportion of which 

 are abnormally modified in various particulars. This diseased condi- 

 tion undoubtedly begins just as soon as the animal is taken out of its 

 natural surroundings. For the cessation of any one set of muscular 

 activities is bound to bring about immediate changes in quantitative 

 metabolism in the system. Change in food supply directly affects the 

 entire organism, and unusual invasion by parasites ensues with con- 

 comitant irregular growths. How then can we expect to get a knowl- 

 edge of the processes of species formation under natural conditions 

 from the extraordinary physical development or behavior of such 

 animals ? 



I would urge that it is only through the close and long-continued 

 study of animals in the wild state, that is, under perfectly natural 

 conditions, that we can hope to gather conclusive evidence as to the 



