i GENERAL PHYSIOLOGY OF MUSCLE 51 



employed by psychologists and clinicians as well as physiologists. 

 The method is universally allowed to make functional isolation of 

 a limited group of muscles possible ; average weights (.'5-4 kgrms.) 

 should be used to ensure the better graduation of the work and 

 curves that are neither too short nor too long ; and it is assumed 

 that the output of work with this load and under the right experi- 

 mental conditions for the ergograph is a true expression of the 

 physiological capacity of the muscle in relation to the weight. 

 Above all, psychologists and psychiatrists sought - - on the 

 strength of Mosso's results, and obviously going farther than he 

 originally attempted to emphasise that both central and peri- 

 pheral or muscular fatigue were shown in the curve. Kraepelin 

 affirmed that in the ergographic curve the height of lift expresses 

 muscular fatigue ; the number of contractions, on the contrary, 

 gives the measure of mental fatigue. This proposition includes 

 the conception that the cessation of the ergograph curve is due to 

 muscular exhaustion, i.e. functional incapacity of the nerve-muscle 

 apparatus, caused in all probability by the curarising action 

 of the fatigue products, owing to which the psychical impulses 

 encounter an increasing resistance. 



In fact, the experiments of many workers upon the influence 

 on the ergograph curve of different external conditions (as 

 temperature, pressure, time of day, etc.), as well as of many internal 

 states (state of nutrition, period of digestion, special diet, exhibi- 

 tion of stimulating agents, of organic extracts, etc.), have always 

 yielded very uncertain results. The output of external mechanical 

 work never varied perceptibly from the ordinary physiological 

 limits. 



U. Mosso attempted by a series of experiments to determine 

 whether the administration of foods sugar in particular could 

 restore the potential capacity of the muscle depressed by work. 

 The most definite conclusion was that the action of sugar was only 

 beneficial with the ergograph when the individual was in a condition 

 of extreme fatigue. 



Generally speaking, the ergograph is not suitable for solving 

 these questions Zuntz and his pupils utilised it, but only as an 

 index to the state of fatigue on certain occasions when the subject 

 was executing a definite piece of work that involved the musculature 

 of the whole body. If the subject is made to do a known quantity 

 of work in the interval between the ergographic records, a per- 

 ceptible recovery is seen in the next ergogram if small quantities 

 of food are administered. 



The value of the ergograph curve as an index of muscular 

 fatigue on the one hand and mental fatigue on the other, as 

 Kraepelin has used it, is very doubtful. 



In 1898 Treves, working in the Physiological Institute of 

 Turin on the laws of muscular activity in man and animals, made 



