i 4 o COMPARATIVE PHYSIOLOGY OF THE BRAIN 



localisation too high up. We wish to emphasise the 

 fact that the frogs from which Schrader removed the 

 whole brain, including the pars commissuralis, not 

 only moved but were still able to climb. The con- 

 dition of rest which appears after injury to the thala- 

 mus is thus not due to the loss of spontaneity. Steiner 

 has also attempted to localise locomotion in a " cen- 

 tre." He found that frogs after losing the pars com- 

 missuralis of the medulla made no more progressive 

 movements, and concluded from this that the sole 

 and undivided control overall locomotions of the body 

 belongs to this part (5 and 6). Schrader's contradic- 

 tory results overthrow Steiner's conclusions. The 

 latter author evidently made his observations on mor- 

 ibund animals, for his frogs survived the operation 

 only a week at the most, while Schrader's lived many 

 months and entirely recovered from the operation. 



According to the segmental theory, on the other 

 hand, it is to be expected that only those parts of the 

 central nervous system are necessary for locomotion, 

 which correspond to the segments of the muscles of 

 the arms and legs. Thus it must be possible to ob- 

 tain coordinated locomotion as long as the segmental 

 ganglia of the muscles of the arms and legs are intact. 

 This agrees with the result obtained by Schrader 

 that after extirpating the whole brain, including the 

 pars commissuralis, coordinated locomotion still oc- 

 curs. We can go still farther and extirpate the whole 

 medulla as far as the tip of the calamus scriptorius 

 and still obtain coordinated locomotion. " Disturb- 



