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Physiology. — "A neir htir coinwriiuKj llw vehdioii hctiriun st'iiini'u'< 

 ami effect." By Prof. .1. K. A. Wkrtiikim Salomonson (6^'^ 

 Coiiuiiuiiication). (Communicated by Prof. C Wixklkr). 

 (Comimuiicaled in the meeting of May 30, 1003) 



Tlio immhors used for testing onr law concern i]i,t>- tlie relation of 

 stimulus and effect, Avere for the greater part derived from lifting-hci'dits 

 in cases of isotoiiical muscle-contractions. During each contraction 

 the tension of the muscle is Jiot perceptil)ly altered, likewise the 

 tension remained the same for all contractions belonging to eacii 

 single series. 



What is the influence of any change of weigiit on the magnitude 

 of the constants? It is known already that the lifting-height changes 

 whenever the tension is changed in any mannei-. In the fornnda, 

 expressing the law for the relation between stimulus and clfect 



the maximum lifting-height is represented by the constant A. As the 

 lifting-height denotes at the same time the maximum quantity of 

 external labour, we may state directly that the constant A will 

 certainly be changed at (my alteration in the magnitude of weight. 



As a matter of course nothing is known about the constant B, 

 neither could I find any indication about the constant C, representing 

 the threshold-value of the stimulus. It is thence of some imporlance 

 to investigate what will happen to the constants B and C, if we 

 alter the weight attached to the muscle. 



To this purpose 1 have recorded a series of isotonical contract i(.)ns 

 of frog-muscles at increasing stimulus. I generally used a gastroc- 

 nemius-preparation, which was stimulated by means of the nerve. The 

 experiments were matle indifferently with muscles cut out or with 

 muscles through which the blood circulated in the normal manner, 

 these offering not the slightest difference between them. 



The stimulus employed, was the current of charge of a condensator 

 of 0.001 microfarad. This was done by pushing down a morsekey 

 mounted on ebonite, thus connecting the condensator with two points 

 between which there existed a known potential difference; in so doing the 

 current of charge of the condensator was led through the nerve of the 

 preparation. When letting go the key the condensator was short-circuited 

 and discharged. The variable difference of tension was obtained by 

 means of a rheochord with platinum-iridium wire, calibrated with the 

 utmost care, through which a constant current was sent by a large 

 accumulator. By means of a variable stccidying resistance care was 

 taken that the P. D. at the ends of the wire, measuring one meter, 



