204: COMPARATIVE PHYSIOLOGY. 



but, leaving this and much more out of the account, it is likely 

 there are individual difPerences in the functional nature of the 

 muscle. Of equal or more importance is the energizing influ- 

 ence of the nervous system, which probably under great excite- 

 ment (public boat-races, etc..) acts to produce in man those 

 supermaximal contractions which seem to leave the muscle 

 long the worse of its unusual action. The nerve-centers, it is 

 likely, suffer still more from excessive discharge of nerve-force 

 (as we may speak of it for the present) necessary to originate 

 the muscular work. Hence the importance of training in all 

 animals to minimize the non-effective expenditure, ascertain 

 the capacity possessed, learn the direction in which weaknesses 

 lie; and equally important the much neglected-period of rest 

 before actual contests — if such are to be undertaken at all — 

 so that all the activities of the body may gather head, and thus 

 be prepared to meet the unusual demand upon them. 



The law of rhythm in organic nature is beautifully illus- 

 trated by the behavior of nerve and especially muscle; at least 

 it is more obvious in the case of muscle, at this stage of our 

 progress. 



The regularity with which one phase succeeds another in a 

 single contraction ; the essentially rhythmic (vibratory) chsir- 

 acter of tetanus, fatigue and recovery ; the recurrence of in- 

 crease and decrease in the muscle and nerve currents — ^in fact, 

 the whole history of muscle is an admirable commentary on 

 the truth of the law of rhythm, into which in further detail 

 space will not permit us to enter. 



It is a remarkable fact that the endurance of man, especially 

 civilized man, seems to be greater than that of any other mam- 

 mal. It may be hazardous to express a dogmatic opinion as to 

 the reason of this, but the influence of the mind over the body 

 is unquestionably greater in man than in any other animal ; 

 and, if we are correct in assigning so much importance to the 

 influence of the n&rvous system in maintaining the proper 

 molecular balance which is at the foundation of the highest 

 good of an organism, we certainly think that it is in this direc- 

 tion we must look for the explanation of the above-mentioned 

 fact, and much more that would otherwise be obscure in man's 

 functional life. 



Functional Variations.— We have endeavored, in treating 

 this subject of muscle, to point out how the phenomena vary 

 with the animal, the kind of muscle, and the circumstances 



