POISONING BY PLANTS. GENERAL PRINCIPLES 25 



4. Veratrin on the frog's heart. Pith a frog, expose the heart and take a tracing 

 when perfused with 0.005 per cent, veratrin in Ringer's solution (o.oi per cent, destroys 

 coordination). 



5. Veratrin on the isolated mammalian heart. Prepare the apparatus for the 

 Isolated heart experiment, isolate a cat's heart and perfuse with 0.0002 per cent, veratrin 



in Locke-blood solution. See Figs. 4, 5, 6. 



6. Veratrin on the simple muscle contraction of the frog. Ligate one leg of a 

 frog and give a hypodermic of 0.05 c.c. of o.i per cent, veratrin. After 15 minutes 



FIG. 4. Apparatus as set up to demonstrate the contractions of the apex muscle 

 of "terrapin's ventricle. The glass L-shaped holder should be set on the stand high 

 enough to allow of easy change of solution tubes. The figure shows the tube of physio- 

 logical saline and other details for the better illustration of the mounting of the heart 

 strip. (Greene). 



prepare the veratrinized muscle and take simple muscle contractions to show the form 



of the contraction wave, using a tuning fork to record the drum speed. Compare this 



curve with that of the undrugged muscle. / 



The frog of experiment i may be used to show the veratrin effect on muscle work. 



Stimulate once in three seconds in this experiment, since the relaxation may not be 

 i complete in an interval of two seconds. 



7. Veratrin on the circulation and respiration of a mammal. Take a record of the 

 j blood-pressure from the carotid of an anesthetized dog. Tracheotomize and take 

 ; respiratory tracings. Give i c.c. of i per cent, veratrin in the abdominal cavity. 

 1 When marked cardiac slowing appears cut the vagi and note the effects on the heart. 



