774 Dynamic Theory. 



There are, indeed, muscular movements resulting from cerebral actions 

 which at first appear to justify the title of involuntary, in the ordinary 

 meaning of the term. Thus the squirming and laughing which result 

 from tickling, may be simply the reflex action of the lower centers 

 medulla, spinal cord, &c. ; but if they result from merely pointing the 

 finger and raising the s uggestion. of. tickling, they are caused by reaction 

 from cerebral memory organs. Nevertheless, on reflection, we shall see 

 that such actions have no right to a classification independent from 

 other cerebral actions. There is no dividing line and no place for one. 

 There may be great differences in the facility with which certain muscles 

 respond when stimulations overflow from certain cerebral organs or com- 

 binations of organs. 



There are, in fact, certain definite relations in some cases between a 

 certain muscle and a particular brain organ, so that it is an established 

 habit, that when the latter is stimulated, the stimulus passes on to the 

 former. In other cases, and generally in complicated and occasional 

 cases, the action is contingent and antecedently problematical, but it 

 is still worked out by the cerebral currents upon the lines of least re- 

 sistance, just as the more simple and definite cases are, and is just as 

 mechanical as they. In all cases, whether it arouses a sensation of . 

 itself or not, there must be the chain of nervous movements, long or 

 short, extending from the memory organ or organs, to the muscle, and 

 it must contain the link or links which, when we are conscious of them, 

 we call the will. 



As observed in chapter 60, there is a class of actions which are co- 

 ordinated in the medulla oblongata, and executed in the various mus- 

 cles, especially those of the face, throat, &c. , which are called expres- 

 sions. The surplus stimulation accumulating in the medulla, overflows 

 to these muscles, and would alone give them certain sorts of tensions 

 and contractions which would constitute the expression of medullary 

 states or conditions. I suppose the face of a complete idiot reflects the 

 expression which stimulations from the medulla oblongata alone would 

 give. But this expression is interfered with by stimulations from the 

 cerebrum. The cerebrum, like the medulla, accumulates a surplus of 

 nervous energy, which likewise flows off and adds its influence to that of 

 the medulla, and modifies the expression of the face, &c. , given by it. 

 It is easy to distinguish the expression of the lower centers from that of 

 the upper. We speak of an idiotic expression and an intelligent ex- 

 pression. But there are all degrees 'of intelligent expression, as there 

 are all degrees of cerebral development and excitement. We can per- 

 ceive the change in the expression of an infant as it begins to accumu- 

 late ideas. The stimulation which finds its outlet in muscular expres- 

 sion, comes from the same sources (the cerebral organs) which, when 



