THE PHENOMENON OF CONTRACTION. 49 



In such a record we can easily calculate the total work done by 

 obtaining the product of the load into the lift for each contrac- 

 tion and adding these products together. By this means the 

 capacity for work of the muscle used can be studied objectively 

 under varying conditions, and many* suggestive results have been 

 obtained, some of which will be referred to specifically.* It should 

 be borne in mind, however, that the ergograph in this form does 

 not enable us to compute the total work that the muscle is capable 

 of performing. It is obvious jthat when the point of complete 

 fatigue is reached, as illustrated in the record, Fig. 24, the muscle is 

 still capable of doing work, that is external work, if we replace the 

 heavy load by a lighter one. For this reason some investigators 

 have substituted a spring in place of the load,f giving thus a 

 spring ergograph instead of a weight ergograph. Although with the 

 spring ergograph every muscular contraction is recorded and the 

 entire work done may be calculated, it also possesses certain theo- 

 retical and practical disadvantages, for a discussion of which refer- 

 ence must be made to the authors quoted. 



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 

 muscle (M. flexor digitorum 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 still further contract the muscle 

 greatly prolong this period of complete recovery, a fact that 

 demonstrates 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, improved circulation in the muscle produced by 

 massage, for example 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) The total amount of work that can be 

 obtained from a muscle is greater with small than with large loads, 



* Mosso, "Archives italiennes de biologic," 13, 187, 189; also Maggiora, 

 1890, p. 191, 342. Lombard, "Journal of Physiology," 13, 1, 1892. 



f Franz, "American Journal of Physiology," 4, 348, 1900; also Hough, 

 ibid., 5, 240, 1901. 

 4 



