ORGANIC MOVEMENTS 103 



the physiological importance of the so-called lower brain- 

 centres in vertebrates. Pfliiger was the first to speak of a 

 " Kiickenmarksseele," that is, of the faculty of the spinal cord 

 of frogs that had been deprived of their whole brain to 

 react to stimuli in a manner which resembles action. But 

 later researches have left it doubtful whether these reactions 

 of the spinal cord really deserve the name of acting, it being 

 perhaps more probable that there occurs nothing but a con- 

 secutive line of different single motions in correspondence to 

 a permanent stimulation which has not been removed by 

 the first or second of them. We have seen already that 

 Jennings has found such a sort of behaviour besides real 

 acting in the infusorium Stentor, and that there is no 

 reason for speaking of actions in such cases. 



It was Goltz who showed for the first time that frogs 

 deprived of the hemispheres, but possessing more of their 

 central system than the mere spinal cord, are capable of 

 reactions which to speak in our own terminology show 

 most clearly the two fundamental characters of action : the 

 " historical basis " and the " individuality of correspondence." 

 Schrader afterwards proved the same to hold for the nervous 

 system of birds, and finally we have the experiments carried 

 out by Goltz on a dog with no hemispheres at all. 1 



What these animals performed, was indeed much less 

 than what they would have done with the use of the parts 

 removed. But, after all, they did " act " in the true sense 

 of the word : obstacles were avoided, even if one of the legs 

 was made helpless ; there were reactions to specific optic 



1 Pfliiger, Die sensorischen Funktionen des Ruckenmarks, 1853 ; Goltz, 

 Beitrdge zur Lelire von den Funktionen der Nervencentren des Froschcs, 1869 

 and Pfliiger's Archiv, 51, 1892. Schrader, ibid. 41, 1887, and 44, 1889. 



