EVOLUTION AND ITS CONSEQUENCES. 31 



6. On the Origin of Intelligence, 



Leaving this part of the subject, we approach one of higher 

 interest, viz., the effects of the metaphysical or mental acquire- 

 ments of animals on their exertions in effort and use. The growth 

 of the mind in animals has, no doubt, followed the same laws 

 obeyed by that of man ; the difference being that the lower forms 

 have remained permanently fixed in stages early passed by the 

 lord of living beings. The foundation qualities from which all 

 the phenomena of intellect may be derived are, the powers of re- 

 tentiveness (memory) and of perceptions of resemblance and dif- 

 ference. These traits are well known to be possessed by many 

 animals, and perhaps in some degree by all. Their possession 

 will be modified by the power of exercising attention, which, in 

 its turn, will depend on the sensitiveness of the animal to impres- 

 sions^n other words, the ease with which consciousness may be 

 aroused. 



The origin of the disposition to take food will be the rudiment 

 of all that appears as ivill in higher animals, and which, though 

 supposed to guide, is the creature of so many stimuli. This ori- 

 gin is supposed by metaphysicians to be the result of education 

 of the '* spontaneous activity" of animals by their pleasures and 

 pains. 



The brain of man and of other animals is an organ which re- 

 ceives and retains pictures and impressions, both painful and 

 pleasurable. The retention of these pictures is not a state of con- 

 sciousness, but they may be brought into the consciousness accord- 

 ing to the law of "contiguity," or association. That is, that the 

 recurrence in the actual of some object or event, which was per- 

 ceived on a former occasion, at or near the same time as another 

 object or event not again repeated in the actual, will bring the 

 latter before the consciousness. So, also, the revival of one such 

 picture will bring within the mental vision others impressed on 

 the mind at or near the same time as the first. These events may 

 have been in the reality either painful or pleasurable. On the 

 recurrence of circumstances which on a former occasion resulted 

 in pain, the resuscitation of the mental picture, then impressed on 



acquisition and inheritance is illustrated by the plantain, Plantago majoy. Although 

 without axis, it has been observed by James C. Cresson, in the Philadelphia Park, 

 and Alfred Cope, on his drive, to force itself through a solid bed of hard vulcanite 

 pavement, several inches in thickness. 



