2 3 



PRACTICAL PHYSIOLOGY. 



[XLIV. 



Apparatus. In a prismatic piece of wood, H, firmly fixed to a base, a hole 

 is cut down to the level, K, through which one can conveniently place one's 

 hand (fig. 153) ; the ulnar surface of the hand rests on the rounded lower end 



of the hole, while the thumb rests 

 against the lateral wall of the hole, 

 so that in this way the hand is 

 sufficiently fixed. Over the index- 

 finger is placed a collar made of 

 strong iron wire, and through this 

 collar project the three other 

 fingers, which hang free, the collar 

 itself lying over the joint between 

 the second and third phalanges. 

 To the collar is attached a strip ot 

 iron with a notch in it, by means of 

 which it is attached to the axis of 

 the lever, which is one so arranged 

 as to give isometric contractions as 

 in fig. 153- 



When one attempts to raise the 

 index-finger, the muscle records an 

 isometric curve. As the collar can 

 at most move only I mm., and as 



Fia. 153. Fick's Apparatus for Studying Ten- 



the muscle itself acts on a lever 

 about five times shorter than the 

 distance of the point of attachment 



collar, acting through B ou an axle, N, to 01 the collar from the axis of rota- 

 which a lever is attached. Seen from the tion of the index-finger, the muscle 

 end - can at most contract \ mm. The 



muscle records on a revolving 



surface. (From the description of Schenk. See Fick, Pfluger's Archiv, Bd. 

 41, p. 176.) 



With this apparatus one can study (i) The force of contraction ; (2) The 

 effect of fatigue and recovery ; (3) One may excite the muscle by means of 

 electricity ; (4) One may compare the mechanical response elicited by electrical 

 (tetanic) and the normal physiological stimulus, and learn that during a 

 voluntary contraction there is a greater contraction, i.e., a greater liberation 

 of energy than during the strongest contraction elicited by electrical stimu- 

 lation. 



2. Mosso's Ergograph for Fatigue and Work. This is a most useful 

 instrument (fig. 154), by means of which the student can study the process of 

 fatigue on himself, the conditions that predispose to it, and the process of 

 recovery, as well as the effect of various conditions on the fatigue-curve. By 

 means of this instrument also the amount of work done is recorded graphic- 

 ally, and can be estimated in terms of kilogrammetres, the contractions in 

 this case being isotonic. The forearm is fixed by means of clamps upon an 

 iron framework, while the hand also is firmly fixed, the index and ring 

 fingers being placed in brass hollow cylinders, while the middle finger is free. 

 The forearm is placed in a half-supinated position. To the middle finger is 

 attached a cord, passing to the writing-style, and to the latter is attached a 

 weight, which can be varied. The style writes upon a recording drum 

 moving horizontally. The forearm is fixed in the apparatus, and the middle 

 finger attached to the writing apparatus, and to the latter is added a load of 

 known weight, e.g., 2-3 kilos. The experimenter flexes the middle finger, 

 lifts the load, and as soon as the contraction is over the load extends the 



