66 



EXPERIMENTAL PHARMACOLOGY 



frenum. Pick this up with the forceps, sever it, and at the 

 point where it is attached to the heart stick the pin hook 

 (which should be small) through the tip oP the ventricle. 

 Adjust the heart lever to write about one-half inch from 

 the lower edge of the drum and see to it that the tracing 



N.GIosso- 



Lei/ator 

 anquli scapulae 



C 'a nation of 

 Sympathetic/chain 



Art- Subdavian 



Spinal 



nerves 



Vertebral 

 column 



Descending 

 Aorta 



(After Oaskell) 



Fig. 61. Diagrammatic dissection to show the origin and course of the sympa- 

 thetic chain and the union of the vagus and the sympathetic fibers for the heart in the 

 frog (Gaskell). 



Fig. 62. Heart lever. The rod is made of 3/16 inch round brass rod into the end 

 of which a small hole is drilled. A small block of wood fiber or hard rubber is attached 

 to the rod by a small wire nail which passes (loosely) through the wood fiber block and 

 is then driven (tightly) into the hole in the end of the rod. The writing lever is a 

 very thin strip split from a long (10 or 12 inches) section of a bamboo fishing pole. 

 This lever, which is very light and limber, passes (tightly) through an oblong hole in 

 the upper part of the wood fiber block. A paper or celluloid (used photographic film) 

 writing point is attached by mucilage or by a cement made by dissolving a photographic 

 film in acetone. These levers are entirely satisfactory for the hearts of frogs, turtles, 

 for uterine strips, etc. They can be made easily and cheaply. 



