136 AFRICAN GAME ANIMALS 



As regards birds and mammals, we are in a position to 

 draw from our studies certain tentative conclusions. 



The first and most important is that both the ultra 

 natural-selectionists and the ultra adherents of the doctrine 

 of the inheritance of acquired characteristics are almost 

 completely in error in their claims that they satisfactorily ex- 

 plain the origin of species. Mere closet theorizing is almost 

 worthless, and artificial experiments are insufficient. What 

 is needed in addition to such experiments is observation of 

 animals in a state of nature, carried on by trained, compe- 

 tent, and open-minded men, desirous of finding out the 

 truth. A book like Mr. Thayer's (in spite of the artistic 

 value of some of his theories) is, we are compelled to say, in 

 its sum a hinderance and not a help to earnest students. 

 His first main contention is that concealing coloration is 

 universal, or nearly so, and sufficient to account as a present- 

 day factor for all present-day coloration. This is in flat 

 contradiction of the facts as regards the immense majority 

 of birds and mammals. His second main contention is 

 that the counter-gradation of shadings is the main factor in 

 producing concealing coloration. As a matter of fact, the 

 countershading of a mammal's or bird's coat, when it 

 exists, is never more than a minor factor in concealing it, 

 and in the immense majority of cases is a negligible factor. 

 It is almost certain that it is not a survival factor, at least 

 with regard to the higher vertebrates, and has not been 

 developed by natural selection working toward the produc- 

 tion of concealing coloration, but is due to some principle 

 or law, such as that at work in the vegetable world, which 

 tends to make leaves darker on their upper than their un- 

 der surfaces, and similarly affects fruits. Under certain cir- 



