488 



SCIENCE. 



risr. S. Vol. II. No. 41. 



which he calls an ' ergograph,' to measure the 

 normal variations of muscular force in man. 

 The work contains illustrations of the apparatus 

 in question, as well as the various curves ob- 

 tained by the experiments. The instrument 

 consists : (1) of a small cushioned platform 

 upon which the forearm rests, fastened down 

 at the wrist in such a manner as to give free 

 play to the fingers, the hand remaining immo- 

 bile meanwhile ; (2) a pulley, consisting of a 

 wheel and cord, one end of which is attached 

 to a weight and the other end to the finger to 

 be experimented upon — usually the middle 

 finger. To this cord, moving in a groove, is 

 fixed a sliding pen, the point of which rests 

 upon the registering cylinder above. At inter- 

 vals of two seconds, marked by the metronome, 

 the subject is expected to concentrate all his 

 force on the muscles of the middle finger for 

 the purpose of lifting the weight at the other 

 end of the cord. The weight thus lifted was 

 usually 8 kg. The line passing through 

 the maxima of the contractions formed the 

 curve of fatigue. 



Experiments of this character are open to 

 theoretical objection. It is evident, from the 

 curves obtained by the registering cylinder, 

 that the digital contractions are in no case in- 

 stantaneous, and that each portion, or part, of 

 a given contraction differs ft-om the preceding 

 or succeeding one. However, the conditions of 

 M. Mosso's experiments were practically such 

 that the variations of time between the differ- 

 ent fractions of contraction were but slight. 

 For all practical purposes, then, the curve thus 

 obtained may be considered a curve of instanta- 

 neous effort in equal intervals of time. 



Similar experiments, made upon himself by 

 M. Aducco, a fellow- worker of the author, show 

 two curves — one obtained in winter, the other 

 in summer. They are not alike. These curves 

 vary not only for different subjects, but also for 

 the same subject under various conditions de- 

 pendent upon the state of health or preceding 

 muscular effort. 



There is also given a curve of fatigue pro- 

 duced by an interrupted current applied in 

 the same manner to the median nerve. The 

 intensity was not at its maximum, but the au- 

 thor affirms that an increase of intensity aug- 



ments but feeblj' the amplitude of the contrac- 

 tions. The curve thus obtained is essentially 

 the same as that obtained by muscular contrac- 

 tions under the influence of the will, fi-om which 

 he concludes that physical fatigue is a phenom- 

 enon depending on the muscles rather than on 

 the excitability of the nervous centers. Never- 

 theless, if we consider an effort of the muscles 

 excited by the will and an effort of the muscles 

 excited by electricity simultaneously, we find 

 the former much greater than the latter. 



It is known that fatigue engenders poisoning, 

 and that the blood of an animal in this abnor- 

 mal state, injected into another animal, will 

 produce all the phenomena of fatigue. When 

 the leg of a frog that is being operated upon be- 

 comes fatigued, the poison may be, so to speak, 

 neutralized, and the contractions may be made 

 to continue by injecting salt water in the 

 artery which carries the blood to the muscles. 

 In case of a total absence of blood, its place 

 may be wholly supplied by salt water. The 

 frog may in this manner be kept alive one or 

 two days and continue to react during the first 

 few hours like a frog in normal condition. 



These poisons, under the name of ptomaines, 

 are now being studied. But until we obtain the 

 knowledge which will enable us to neutralize 

 them chemically, it is well to know that their 

 elimination may be facilitated by all the vari- 

 ous operations calculated to accelerate respira- 

 tion, massage, etc. 



Severe intellectual labor diminishes the pulse, 

 produces a fullness in the head, causes palpita- 

 tion of the heart, pain in the brain and in the 

 muscles of the eye, sometimes photophobia and 

 often vertigo. Dyspepsia, also, is among its pain- 

 ful consequences. Violent muscular exercise has 

 been prescribed as a remedy for all these ills, 

 but this is shown to be a mistake. The only 

 remedj"^ is rest^ — a complete cessation of mental 

 labor, the disturbing cause. The fact is that, af- 

 ter a prolonged physical effort, nervous excite- 

 ment increases in proportion as muscular energy 

 diminishes, and this excitement is apt to extend 

 to other muscles which should not be brought 

 into participation. 



Another device of M. Mosso, a modification 

 of the ergograph, which he calls the jmnometre, 

 permits him to measure this travail a ride, as he 



