434 EXPERIMENTAL PHARMACOLOGY 



tion. The animal after a time will be able to jump very well 

 but will alight with the hind legs extended and the fore legs 

 passed back along the flanks. Only with difficulty can the 

 animal then draw up its hind limbs. What is the cause of 

 this difficulty? After some time (if the dose was large 

 enough) the animal becomes completely paralyzed and dies. 

 Then expose the heart and note whether it stopped in 

 systole or diastole. In what condition does the heart usu- 

 ally stop? Is this true for a mammal also! What can you 

 say of the general action of veratrine ? 



EXPERIMENT CXL. 



Veratrine. (Frog or Turtle: Heart and Inhibitory 



Apparatus.) 



1. Arrange a frog or turtle for taking heart tracings. 

 Make a normal record (showing both vagus trunk and cres- 

 cent inhibition). Pour a few drops of veratrine (sulphate 

 or hydrochloride) solution (ten cubic centimeters equal one 

 milligram) on the heart and record the effect. After the 

 drug has acted a few moments stimulate the vagus nerve 

 again and see if the heart is inhibited. Also stimulate the 

 crescent and see what happens. What conclusions can you 

 draw ? Apply more of the drug and record the full action 

 on the heart. Is there any visible difference between the 

 action on the ventricle and that on the auricles? AVould 

 your method of suspension obscure the appearance of the 

 behavior of the heart under the drug : ; 



EXPERIMENT CXLI. 

 Veratrine. (Frog: Skeletal Muscle.) 



1 . Set up your apparatus as si i own in Experiment XL VII, 

 p. 245 (see also Experiment XCVI under cocaine), for re- 

 cording muscular contractions. Then pith a frog and ligate 



