728 THE POPULAR SCIENCE MONTHLY, 



these occur, as, for example, when a man in falling mechanically puts 

 out his hands to save himself. "In these cases," Descartes said, "I 

 have clear evidence that the nervous system acts mechanically without 

 the intervention of consciousness, and without the intervention of the 

 will, it may be in opposition to it." Why, then, may I not extend 

 this idea further ? As actions of a certain amount of complexity are 

 brought about in this way, why -may not actions of still greater com- 

 plexity be so produced ? Why, in fact, may it not be that the whole 

 of man's physical actions are mechanical, his mind living apart, like 

 one of the gods of Epicurus, but unlike them occasionally, interfering 

 by means of his volition ? 



And it so happened that Descartes was led by some of his specu- 

 lations to believe that beasts had no soul, and consequently, according 

 to his notion, could have no true mental operations, and no conscious- 

 ness ; and thus, his two ideas harmonizing together, he developed that 

 famous hypothesis of the automatism of brutes, which is the main 

 subject of my present discourse. What Descartes meant by this was 

 that animals are absolutely machines, as if they were mills or barrel- 

 organs ; that they have no feelings ; that a dog does not hear, and 

 does not smell, but that the imj^ression which thus gave rise to those 

 states of consciousness in the dog gave rise by a mechanical reflex 

 process, to actions which correspond to those which we perform when 

 we do smell, and do taste, and do see. Suppose an experiment. Sup- 

 pose that all that is taken away of the brain of a frog is what we call 

 the hemisphere, the most anterior part of the brain. If that operation 

 is properly performed, very quickly and very skillfully, the frog may be 

 kept in a state of full bodily vigor for months, or it may be for years ; but 

 it will sit forever in the same spot. It sees nothing; it hears nothing. 

 It will starve sooner than feed itself, although, if food is put into its 

 mouth, it swallows it. On irritation, it jumps or walks ; if thrown into 

 the water, it swims. But the most remarkable thing that it does is this 

 — you put it in the flat of your hand, it sits there, crouched, perfectly 

 quiet, and would sit there forever. Then if you incline your hand, doing 

 it very gently and slowly, so that the frog would naturally tend to slip 

 off*, you feel the creature's fore-paws getting a little slowly on to the 

 edge of your hand until he can just hold himself there, so that he does 

 not fall; then, if you turn your hand, he mounts up with great care and 

 deliberation, putting one leg in front and then another, until he bal- 

 ances himself with perfect precision upon the edge of your hand; then 

 if you turn your hand over he goes through the opposite set of oj^era- 

 tions until he comes to sit in perfect security upon the back of your 

 hand. The doing of all this requires a delicacy of coordination and 

 an adjustment of the muscular apparatus of the body which are only 

 comparable to those of a rope-dancer among ourselves ; in truth, a frog 

 is an animal very poorly constructed for rope-dancing, and on the whole 

 we may give him rather more credit than we should to a human dancer. 



