196 The Unity of the Organism 



frog's brain are not uncommon, and as the facts are spe- 

 cially important for u.s, it is desirable to consider the evi- 

 dence a little more in detail. To this end the following from 

 Holmes may be taken as an authoritative summing up of 

 results so far reached in this field. "A frog; with the brain 



o 



removed as far back as the medulla is still capable of per- 

 forming regular leaps and swimming movements of the 

 limbs. When thrown on its back it rights itself, and still 

 performs compensatory motions when tilted or rotated. 

 Breathing is normal, and the animal swallows pieces of food 

 that are placed in its mouth." 12 



If the removed portion of the brain is made yet larger, 

 by including the anterior part of the medulla, the animal is 

 still capable of performing a long series of regular activi- 

 ties. "Locomotion is effected mainly by creeping, but the 

 frog is nevertheless capable of springing in the ordinary 

 manner. In the water it swims by alternate movements of 

 the limbs. . . . The breathing and swallowing reflexes are 

 still normal, but the croaking reflex is no longer performed. 

 The reflex of snapping at food is not destroyed. ... If a 

 piece of meat is rubbed against the frog's nose, the animal 

 snaps at it and uses the fore legs to stuff it into the mouth. 

 The same reaction may be brought about by using the finger, 

 but after the finger is seized and it is found that the object 

 is too large to be stuffed into the mouth, the frog begins to 

 reject the morsel, and uses the fore legs to push it away. 

 Truly a remarkable combination of reflexes!" 12 



And further : "There is no center for coordinated locomo- 

 tion in the medulla. Disturbances of locomotion begin with 

 the fore limbs. If the medulla is cut across at the tip of 

 the calamus scriptorius, the animal sinks on its breast, and 

 the fore limbs are for a considerable time helpless, although 

 the hind limbs are capable of performing vigorous coor- 

 dinated movements. The reason for this is that the injury 

 lies so near the region from which the nerves of the fore 



