THE RECORDING OF MUSCULAR CONTRACTIONS 31 



usual way. If the speed of the drum is the same as before (one 

 revolution per second), the curve is more prolonged than that of the 

 gastrocnernius, for the contraction of the hyoglossus is slower than 

 that of the gastrocnernius. It is well, however, in investigating the 

 action of veratrin to use a slow rate of cylinder, since this drug enor- 

 mously delays the relaxation of muscle. The cylinder therefore 

 should be arranged to revolve once in about ten seconds. 



A normal muscle curve is first described, the point of stimulation 

 being marked in the usual way. Then inject with a hypodermic 

 syringe a drop or two of veratrin acetate solution (1 in 300) under the 

 mucous membrane of the tongue, so that the drug is brought into 

 contact with the fibres of the hyoglossi. After three minutes take 

 another muscle curve. Describe a tuning-fork tracing below the 

 abscissa. If the preparation is excited repeatedly, it will be found 

 that the contractions lose their prolonged character, which, however, 

 returns after a period of rest. 



This method can be used for investigating the action of other drugs upon 

 muscular contraction. 



