CHEMICAL AND MECHANICAL STIMULATION 167 



twitch of the whole of the fibre stimulated will 

 precede the continued local contraction or wheal. 

 The same phenomenon is seen for - a briefer 

 time on sharp mechanical stimulation of muscles 

 in living animals, for example, the wheals raised 

 by the blow of a whip. In men long ill of wast- 

 ing diseases, e. g. phthisis, the idio-muscular con- 

 tractions appear on drawing a pencil point across 

 the muscles. Direct total stimulation of frog's 

 muscle, especially in the spring months, may be 

 followed by long continued contraction. Fatigue, 

 cold, and many poisons, such as veratrine, favor 

 the prolongation of the phase of shortening. The 

 idio-muscular contraction is not a " tetanus," 

 i. e. not a prolonged shortening due to successive 

 contractions, the interval between which is too 

 short to permit of relaxation, but a prolonged 

 single contraction, the cause of which lies in the 

 muscle and not in the nerve. 



APPARATUS 



Normal saline. Bowl. Pipette. Towel. Glass plate. 

 Distilled water. Sodium chloride. Solution of sodium 

 chloride (0.6 per cent), containing 10 per cent of saturated 

 solution of calcium sulphate. Solution containing 5 grams 

 sodium chloride, 2 grams di-sodium hydrogen phosphate, 

 and 0.4 gram sodium carbonate, in 1000 c.c. water. Small 

 warm-blooded animal recently killed. Introduction coil. 

 Dry cell. Key. Electrodes. 3 Wires. Frogs. 



