260 THE BRAIN OF QUADRUPEDS AND 



the Intelligence of the respective creatures ; neither shall 

 we find that it in the least degree harmonizes with the 

 complexity of development to which the Brain attains. 



One of the principal disturbing causes arises from the 

 fact, that in animals of any given order, the bulk or 

 weight of the Brain when passing from its smaller 

 to its larger representatives, does not increase at all 

 in the same proportion as the total body- weight of such 

 animals. Some striking illustrations of this fact have 

 been cited by Professor Owen.* Small and large repre- 

 sentatives of the same order of animals are, in the sub- 

 joined list, bracketed together, in order to show how much 

 greater is the ratio of brain- weight to body- weight in the 

 diminutive forms. 



1 : 95 



1 : 764 



1 : 90 



1 : 500 



1 : 20 

 1 : 200 



In part explanation of these very interesting peculiari- 

 ties, Prof. Owen advances the following hints. " The 

 Brain," he says, " grows more rapidly than the body, and 

 is larger in proportion thereto at birth than at full 



growth So in the degree in which a species 



retains the immature character of dwarfishness, the brain 

 is relatively larger than the body." This may be to some 

 extent an explanation of the peculiarity above shown to 

 exist ; but there are, doubtless, other vital and mechanical 

 reasons, why the bulk of the Brain should not increase 

 quite proportionately with the bulk of the body. 



We may now point out some of the more striking pecu- 

 * "Anat. of the Vertebrates," iii.p. 143. 



