Functions of the Medulla Oblong ata. 613 



tion with the spinal cord in actions purely reflex, and often quite com- 

 plicated, and executed as well in the absence of sensation as when it is 

 aroused. If from a frog the cerebrum be removed, with care not to in- 

 jure the optic lobes, or any of the nervous system back of them, the 

 frog ma}^ be kept alive and in full bodily vigor for months or even years. 

 It will not of its own accord move, but sits stationary. It does not 

 seem to see or hear. It will not feed itself, but will swallow food placed 

 in its mouth. "On irritation it jumps or walks; if thrown into the 

 water it swims. If it be put on the hand it sits there crouched per- 

 fectly quiet, and would sit there forever. If the hand be inclined very 

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

 creature's fore pa,ws are shifted onto the edge of the hand until he can 

 just prevent himself from falling. If the turning of the hand be slowly 

 continued, he mounts up with great care and deliberation, putting first 

 one leg forward and then another, until he balances himself with per- 

 fect precision upon the edge, and if the turning of the hand is contin- 

 ued, over he goes, through the needful set of muscular operations, un- 

 til he comes to be seated in security upon the back of the hand. The 

 doing of all this requires a delicacy of co-ordination, and a precision of 

 adjustment of the muscular apparatus of the body, which are only com- 

 parable to those of a rope dancer. " Notwithstanding the animal ap- 

 pears blind, if he be put upon a table with a book at a little distance, 

 and between it and the light, and he then be irritated by a touch on the 

 hind part of the body, he will jump forward, avoiding the book by pass- 

 ing to the right or left of it. 1 It is evident that the frog sees without 

 having the perception of sight. That is, its sight stimulation effected 

 through the retina, is transmitted through the sensory ganglia, and co- 

 ordinated with the stimuli of touch, and has its modifying influence on 

 the motor action developed, without arousing any sensation, just as the 

 touch stimuli alone would cause it to jump blindly and without sensa- 

 tion of the touch. If the brain of the frog be cut away so as to include 

 the optic lobes in the abscinded part, it is still able to sit in its ordinary 

 position, and of itself it would not move. But if touched or stimu- 

 lated in some way it will jump or walk, and if thrown into the water it 

 will swim. The cerebellum with the medulla oblongata and the spinal 

 cord, here comprise a complete governing apparatus for the motor ma- 

 chinery of the frog. 



Goltz obtained examples of quasi purposive movements, and also ex- 

 pressions of satisfaction in a decapitated frog, by stimuli applied to it. 

 The movements of the limbs to rub off acid applied to the skin, have 

 been mentioned. The quack or croak, expressive of satisfaction, he 

 elicited b} r stroking the creature gently on the back, and the movement 



1 See Huxley on Automatism. The first experiment of this kind was made by Goltz, 

 and published in 1869. 



