[ ^PRACTICAL EXERCISES 201 



(c) After an interval'of thirty minutes, again measure the height of 

 the mercury in the manometer. Then bleed the dog to death while 

 a tracing is being recorded. 



26. The Influence of Albumoses (and Peptones) on\the Blood- 

 pressure. Set up the apparatus for taking a blood-pressure tracing 

 as in experiment 22 (p. 195), but omit the induction-coil. Weigh 

 a dog. Weigh out a quantity of Witte's peptone equivalent to 

 0-5 grm. for every kilo of body- weight. Dissolve the peptone in 

 aboutjten times its weight of 0*9 per cent, salt solution. Anaesthe- 

 tize the dog with morphine and ether or A.C.E. mixture. Insert a 

 cannula into the trachea. Put cannulae into the central end of 

 one carotid and of one femoral vein (p. 200) . Connect the carotid 

 with the manometer, and the femoral vein with a burette or large 

 syringe containing the peptone solution. Take care that the 

 connecting-tube and cannula are free from air. Now commence 

 to take a blood-pressure tracing, and while it is going on inject 

 the peptone solution. The pressure falls owing largely to a dilata- 

 tion of the small arteries through the direct action of the peptone 



FIG. 95. EFFECT OF INJECTION OF PEPTONE ON THE BLOOD-PRESSURE 

 IN A DOG. 



(To be read from right to left.) 



on their muscular tissue or on the endings of the vaso-motor 

 nerves.* 



27. Effect of Suprarenal Extract on the Blood-pressure. Make 

 the arrangements for a blood-pressure tracing from a dog as in 22, 

 p. 195. Put a cannula in the carotid and another in the femoral vein 

 or one of its branches (p. 200). Expose both vagi in the neck, and 

 pass threads loosely under them. Connect the carotid with the 

 manometer and take a tracing. Then, while the tracing is continued, 

 inject slowly into the femoral vein an amount of watery extract 

 corresponding to about 0*2 grm. of suprarenal, or, what is more 

 convenient, a few c.c. of a solution of adrenalin chloride of the 

 strength of i to 50,000 in 0-9 per cent, sodium chloride solution, 

 the dose depending, of course, on the size of the animal. The blood- 



* In 12 dogs the blood-pressure always fell, the amount of the fall 

 varying from 81 to 21 mm. of mercury (average, 60 mm.). It sometimes 

 returned to normal in twenty to thirty minutes, but usually required a 

 longer time. In some dogs, after the injection of the whole of this amount 

 of peptone, death occurs before there has been any considerable recovery 

 of the pressure. 



