THE PHENOMENON OF CONTRACTION. 47 



The weight ergograph has so far at least given us the most sug- 

 gestive results. Among these the following may be mentioned: 

 (1) If a sufficient interval is allowed between contractions no fatigue 

 is apparent. With a load of 6 kilograms, for instance, the flexor 

 sublimis showed no fatigue when a rest of 10 seconds was given 

 between contractions. (2) After complete fatigue with a given 

 load a very long interval (two hours) is necessary for the muscle to 

 make a complete recovery and give a second record as extensive as 

 the first. (3) After complete fatigue efforts to contract the muscle 

 greatly prolong this period of complete recovery, a fact that dem- 

 onstrates the injurious effect of straining a fatigued muscle. (4) 

 The power of a muscle to do work is diminished by conditions that 

 depress the general nutritive state of the body or the local nutrition 

 of the muscle used; for instance, by loss of sleep, hunger, mental 

 activity, anemia of the muscle, etc. (5) On the contrary, im- 

 proved circulation in the muscle produced by massage, for ex- 

 ample increases the power to do work. Food also has the same 

 effect, and some particularly interesting experiments show that 

 sugar, as a soluble and easily absorbed foodstuff, quickly increases 

 the amount of muscular work that can be performed. (6) Marked 

 activity in one set of muscles the use of the leg muscles in long 

 walks, for example will diminish the amount of work obtainable 

 from other muscles, such as those of the arm. It is very evident that 

 the instrument may be used to advantage in the investigation of 

 many problems connected with gymnastics, dietetics, stimulants,* 

 medicines, etc. A point of general physiological interest that has 

 been brought out in connection with the use of the ergograph calls 

 for a few words of special mention. Mosso found that if a muscle 

 e. g., the flexor sublimis is stimulated directly by the electrical 

 current and its contractions are recorded by the ergograph, it will 

 give a curve similar to that figured above for the voluntary con- 

 tractions, except that the contractions are not so extensive. Under 

 these conditions the muscle, when completely fatigued to electrical 

 stimulation, will respond to voluntary stimulation from the nerve 

 centers. It seems likely, as suggested by Hough, that this result is 

 due mainly to the fact that the electrical current can not be applied 

 to a muscle in its normal position so as to excite uniformly all the 

 constituent muscle fibers, although it is also quite possible that 

 what we call the normal or voluntary stimulus is more effective, or, 

 to use a physiological term, more adequate to the muscle fibers than 

 the electrical shock. On the other hand, after fatigue from a series 

 of voluntary contractions it has been observed that the muscle will 

 still give contractions if stimulated directly by electricity. This fact 

 has been interpreted to mean that, in the neuromuscular complex 

 * Schumberg, "Archiv f. Physiol./' 1899, suppl. volume, p. 289. 



