ACTION OF SALTS 41 



of a small percentage of soluble lime salt stops them. 

 K salts approximately isotonic with blood plasma (about 

 75 p.c.) cause contraction and rapid death. 



Take the sartorius muscle 1, a, and place it in about 

 20 c.c. of pure NaCl -6 made up in distilled water. In 

 a short time (the time varies with the condition of the 

 muscle) fibrillar twitchings and some more general con- 

 tractions will be seen. Transfer it to a mixture of NaCl 

 6 and CaCl 2 "05 p.c., the spontaneous contractions cease. 

 Put it back in the NaCl -6 p.c., the contractions begin 

 again. Transfer it to a mixture of NaCl -6 and KC1 -2 p.c., 

 the muscle contracts at first more vigorously, then be- 

 comes quiescent, and gradually loses its irritability. 



The twitching of the muscle in pure sodium chloride decreases as 

 the muscle is left in the body after the death of the frog. It is less 

 in winter than in summer. 



3. Action of veratrin. Take the sartorius muscle 

 1, 6, and fasten it in the moist chamber. Arrange the 

 electrodes to touch the upper and lower surfaces, near 

 the ends of the muscle. Fill the chamber with saline 

 solution. With a drum rotating about 10 cm. a sec. take 

 a tracing of a single muscular contraction (p. 23, 2). 

 Leave the lever in position, run off the salt solution, and 

 replace it by '001 p.c. veratrin sulphate made up in 

 saline solution 1 . In about five minutes take a series of 

 5 tracings of the effect of single break induction shocks 

 in the following way. Let the drum revolve continu- 

 ously, and as soon as the break shock is sent into the 

 muscle, close first the key in the secondary circuit and 

 then the knock-down key in the primary, then open the 



1 Dilute solutions of poisons are made up in Ringer's fluid unless there 

 is reason to the contrary. 



