LIFE ON THE EARTH. 137 



interpret, either in its presence, its -absence, or the 

 variations incident to it. 



But the structural relations of the higher mam- 

 malia to man are a preface only to the deeper question 

 regarding the functions severally attached to them. 

 Structural likeness of organ implies likeness or identity 

 of function. Does resemblance of brain, in its various 

 degrees, warrant fully this interpretation ? or is there 

 some specialty here which forbids or limits the appli- 

 cation of the rule ? I confess I know of none. In 

 whatever way the scale of animal life be arranged, 

 there is a certain proportion found to exist between the 

 cerebral development of the species and the presence 

 of those faculties to which the brain ministers in man. 

 This fact must be taken generally, as we are unable 

 to gauge with exactness in other animals qualities 

 and functions which are not easily described or 

 measured even in ourselves. But in such general sense, 

 and restricting the enquiry to the higher animals, we 

 come upon a multitude of recognised facts, which, 

 though escaping serious thought from their familiarity, 

 are cogent and of deep import in the conclusions to 

 which they lead us. 



Even without serious thought, however, common 

 language has fully recognised these facts as they every 

 day come before us. We speak habitually of the 

 varying intelligence of different animals, individuals as 

 well as varieties and species. We speak of their charac- 

 ters and tempers as different, denoting thereby propen- 

 sities, passions, and affections the same in kind which 

 belong to the moral nature of man. I have already 



