608 Dynamic Theory. 



his brains. But in the absence of brain and consciousness there is no 

 possibility that the action could be complicated by any other stimulation 

 than that applied to the particular nerves in question. This irritation 

 has all its own way, therefore, with the irog, and this much of the 

 animal is a machine which, whether in consciousness or not, is equally 

 under the influence of the stimulus, the consciousness, if it is mani- 

 fested at all, being a secondary matter, not antecedent or necessary to 

 the effectual operation of the stimulus, nor contributing anything to it, 

 but arising out of it. In the case of the paralytic patients it must 

 likewise be maintained that the part disconnected from the brain and its 

 influence, is a machine worked exclusively by the influence of the ex- 

 ternal stimuli. 



Ferrier says : < ' It is clear, from an examination of the reactions of 

 the brainless frog, that the movements are not mere muscular contrac- 

 tions of individual muscles, but muscular combinations of greater or 

 less complexity, acting synergically for a definite end. It is obvious, 

 therefore, that the spinal centers are themselves the co-ordinating cen- 

 ters of a great variety of adapted movements. " When there is local 

 disease of certain parts of the anterior horn of the spinal cord, certain 

 synergic or co-operative combinations of muscles become paralyzed; 

 stimulation of the different motor roots of the spinal cord for the limbs, 

 according to the experiments of Ferrier and Prof. Yoe, on monkeys, 

 on the other hand, give rise to the movement of their corresponding 

 limbs in more or less complicated actions. ' < Thus, stimulation of the 

 second dorsal root excites the action of the intrinsic muscles of the 

 hand, as seen when the animal is resting on a perch ; the first dorsal 

 brings into play a great number of muscles, the general result of which 

 may be compared to plucking a fruit and drawing it towards the trunk ; 

 the eighth cervical causes a complication of movements, which brings 

 the tips of the fingers into the position requisite for scratching the but- 

 tocks, the scalptor ani action ; the seventh cervical innervates the mus- 

 cular actions, which, supposing the hands were the fixed point, would 

 cause the body to raise up, as in mounting a branch or trapeze ; while 

 the sixth cervical brings the hand up to the mouth ;" and stimulation of 

 the fifth cervical causes the arm and hand to be raised upwards and 

 backwards. Then the stimulation of various lumbar roots effects vari- 

 ous more or less complicated movements of the legs and toes. 



' ' The experiments of Ward, and also those of Yung, show that in 

 the cray-fish each segment of the ganglionated cord is the center for the 

 movements of the corresponding somite. 1 That the same holds good 

 for the segments of the cord in vertebrates, though perhaps not to the 

 same degree of independence seen in the cray-fish and other members 



1 See Ferrier's Functions of the Brain, 78. 



