46 THE PHYSIOLOGY OF MUSCLE AND NERVE. 



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 that when the point of complete 

 fatigue is reached, as illustrated in the record, Fig. 23, the muscle is 



Fig. 23. Normal fatigue curve of the flexors of the middle finger of right hand. Weight, 

 3 kilograms, contractions at intervals of two seconds. (Maggiara.) 



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 last quoted. 



* Mosso, "Archives italiennes de biologie," 13, 187, 1890; also "Archiv 

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

 1892. 



t Franz, "American Journal of Physiology," 4,348, 1900; also Hough, ibid., 

 5, 240, 1901. 



