SOME INTERNAL STRUCTURES 79 



therefore, to find a lowish type of brain ; instead of 

 this we are confronted with the most specialised. 

 Nothing is more difficult in zoology than to arrive 

 at convenient generalisations- - for the paradoxical 

 reason that it is so easy to frame hypotheses. The 

 expression "simplex sigillum veri," not composed for 

 the purpose for which it is used, and yet used with 

 such frequency in zoological writing, especially in the 

 newer developments of what is called sometimes 

 " Darwinism," has had a most deleterious effect upon 

 speculation. A simple and obvious explanation often 

 seems to such writers to settle the question at issue. 

 And yet in the long run it seems to be plain that 

 the processes of nature are not so simple. It is 

 certain that the brains of some of the early and 

 extinct forms of mammals were not only small but 

 smooth. It is equally certain that their descendants 

 -or at least allied forms subsequent in date have 

 not only larger, but more rumpled brains. The 

 whales, we can fairly assume, are an ancient stock, 

 and may have started even as "whales" with small 

 and smooth brains. The requisite increase was 

 brought about by a more extensive crumpling of the 

 surface, while the small frontal bones and the larore 



O 



development of the facial region of the skull pre- 

 vented the extension of the brain cavity forwards, 

 its extension laterally being permitted partly by the 

 non-union of the parietals above, and by the feebly- 

 attached bony apparatus connected with the organ 

 of hearing. It seems to follow further that the 

 whales cannot be nearly related to any existing form 



