138 THE INFANCY OF ANIMALS 



Years ago, when Huxley turned that penetrating and 

 versatile mind of his to the subject of the classification 

 of birds, he speedily discovered that the accepted systems 

 of the day were mere artificial, mechanical makeshifts. 

 He replaced them with a system which, whatever its 

 defects, was vastly superior to any other hitherto con- 

 ceived of. And this because he realised, what his pre- 

 decessors had not, that the superficial, external likenesses, 

 which animals often present, are absolutely untrustworthy 

 evidences of relationship. It was this criterion of super- 

 ficial resemblances which led the older naturalists to 

 regard the whale as a fish, and the swift and the swallow 

 as nearly related species. 



Huxley, knowing little or nothing about birds, from the 

 ornithologist's point of view, came to his subject without 

 any preconceived notions. He sought to avoid the 

 danger of prejudicing his mind by mere externals, and 

 by turning his attention instead to a study of deep-seated, 

 internal structures, to establish a classification which 

 should express, more or less accurately, the inter-relation- 

 ship of the various groups of birds one to another. He 

 chose, and wisely, to make the skull the corner-stone of 

 this classification. But he left out of account the evidence 

 furnished by young birds ; neither their embryonic nor 

 early post-embryonic characters entered into his calcula- 

 tions. Thereby he missed some extremely important 

 evidence such as he was seeking ; evidence, too, such as 

 his soul loved, pigeonholed as it might have been under 

 the " comfortable word Evolution," for further use in 

 some of those brilliant discourses delivered during his 

 championship of the cause of Darwinism and liberty of 

 thought. 



What then, precisely, were the points which Huxley 



