CHAP. XXIV. INTELLIGENCE OF LOWER ANIMALS. 493 



" Diflferences of degree and differences of kind are^ it is 

 true, mutually exclusive terms in the language of the schoolsj 

 but whether they are so also in the laboratory of Nature, we 

 may very well doubt."* 



The same physiologist suggests that as there is con- 

 siderable plasticity in the human frame, not only in youth 

 and during growth, but even in the adult, we ought 

 not always to take for granted, as some advocates of the 

 development theory seem to do, that each advance in 

 psychical power depends on an improvement in bodily struc- 

 ture; for why may not the soul, or the higher intellectual and 

 moral faculties, play the first instead of the second part in a 

 progressive scheme ? 



Intelligence of the lower Animals compared to that of Man. 



Ever since the days of Leibnitz, metaphj^sicians who have 

 attempted to draw a line of demarcation between the intelli- 

 gence of the lower animals and that of Man, or between 

 instinct and reason, have experienced difiiculties analogous 

 to those which the modern anatomist encounters when he 

 tries to distinguish the brain of an ape from that of Man by 

 some characters more marked than those of mere size and 

 weight, which vaiy so much in individuals of the same 

 species, whether simian or human. 



Professor Agassiz, after declaring that as yet we scarcely 

 possess the most elementary information requisite for a 

 scientific comparison of the instincts and faculties of animals 

 with those of Man, confesses that he cannot say in what the 

 mental faculties of a child differ from those of a young chim- 

 panzee. He also observes that " the range of the passions of 



■-■■ Report of a Lecture delivered at Man and Animals. Medical Gazette, 

 the Royal Institution, by Professor March 15, 1862, p. 2G2. 

 George Rolleston, On the Brain of 



