326 Intelliijence and Miscellaneous Articles. 



normal condition of the muscular fibre, diminishes as the muscle 

 contracts, and disappears when the muscle has attained its maximum 

 contraction. 



M. Weber also measured the absolute force of the gastrocnemian 

 and solear muscles of man, and found it equal to about a kilogramme 

 for each square centimetre of muscle. M. Henke of Rostock, how- 

 ever, found an error of calculation in M. Weber's numbers ; having 

 repeated the experiments with the flexor muscles of the forearm, he 

 found a higher number (that is, 8 kilogrammes) for each square 

 centimetre of human muscle. 



In my researches on muscular contraction I was led to repeat M. 

 Weber's researches on the absolute force of the muscles of the frog. 

 I used a method which is more completely free from the errors pro- 

 duced by the fatigue of the muscle. I have thus found values greater 

 than those of M. Weber. The method is as follows :— 



Imagine the muscle fixed at the upper end by a clamp so strong as 

 not to yield to weights even heavier than those we use ; we suspend 

 to the lower end of the muscle a lever so. light that its weight may 

 be neglected. The axis of rotation of the lever is horizontal, and 

 situated at one end ; at the other end is a platinum wire resting on 

 a plate of the same metal, and allowing the current of a Daniell's 

 battery to pass round an electromagnet. The muscle being fixed in 

 the middle of the lever, the clamp which supports it may be raised 

 until the elasticity of the muscle just brings the lever in contact 

 with the platinum plate. In the middle of the lever, just at the 

 point at which the muscle is fixed, is suspended the plate of a balance, 

 on which are placed the weights which are to measure the force of 

 contraction. These weights do not stretch the muscle ; for the 

 lever rests on the platinum plate ; but during contraction the muscle 

 is compelled to raise these weights. Thus by gradually increasing the 

 number of these weights a sufficiently great value is obtained to pre- 

 vent contraction. So long as the weight has not reached this value, 

 the muscle breaks the circuit at each contraction. When the cur- 

 rent is broken, the contact of the electromagnet is withdrawn by a 

 spring and strikes on a bell. The weight is thus easily found by 

 which the current is not broken — that is, the weight sufficient to 

 neutralize the motion produced by the contractile force of the muscle. 



The absolute force of the muscle being thus found, it is necessary 

 to measure its cross section; and this is effected by dividing the 

 weight of the muscle by the length of the fibres multiplied by the 

 specific gravity of muscle. My experiments have always been made 

 with the muscles of the frog's thigh, which form a regular mass with 

 parallel fibres. They yield better results than those used by M. 

 Weber ; for they present a greater mass, and withstand fatigue better. 

 I found in this manner that the force of contraction of each square 

 centimetre of frogs' muscle varies between T8 and 3 kilogrammes, 

 a value far higher than that of M. Weber. 



The absolute force of the gastrocnemian muscle of a frog of mean 

 size varies between 1000 and 1200 grms. This enormous number is 

 intelligible if we consider that the cross section is very large in pro- 

 portion to its volume. We see thus that muscles are very perfect 



