CLASSIFICATION AND ADAPTATION 19 



through Colorado to the mouth of the Rio Grande 

 on the Gulf of Mexico. Between the two areas thus 

 roughly defined is a tract of country about 300 to 

 400 miles wide, which contains some normal birds 

 of each type, but chiefly birds exhibiting irregular 

 mixtures of the characters of both. Bateson re- 

 marks that some naturalists may be disposed once 

 more to appeal to our ignorance, and suggest that if 

 we only knew more we should find that the yellow 

 quills, the black ' moustache,' and the red nuchal 

 crescent specially adapt auratus to the conditions of 

 the northern and eastern region, while the red quills, 

 red moustache, and absence of crescent fit cafer to 

 the conditions of the more southern and western 

 territory. But, as the author we are quoting 

 points out, when we think of the wide range of con- 

 ditions in the country occupied by auratus, extend- 

 ing from Florida to the Arctic, it is impossible to 

 believe that there is any common element in the 

 conditions which demands a scarlet nuchal patch in 

 auratus, while the equally varied conditions in the 

 cafer area do not require that character. It may be 

 added that the same objection is equally valid 

 whether we apply it to the utility of such a character 

 or to the supposition that the character has been 

 caused by external conditions; in other words, 

 whether we attempt to explain the facts by selec- 

 tion or by the Lamarckian principle. 



Another case quoted by Bateson is that of the 

 two common British Wasps, Vespa vulgaris and 

 Vespa germanica. Both usually make subter- 

 ranean nests, but of somewhat different materials. 

 That of V. vulgaris is of a characteristic yellow 

 colour, because made of rotten wood, while that of 



