26 SUPRAKENAL GLANDS. 



maximum blood pressure and the time which elapses before the blood 

 pressure returns to normal is likewise noted and compared with the 

 standard. At intervals of five or six minutes various amounts of this 

 fluid are injected, until an amount is injected which gives a rise which 

 corresponds to the 1 c. c. of the standard solution. This injection 

 should be repeated several times, changing the order of the injection, 

 and a mean taken, and finally the correct solution and the standard 

 one injected into a fresh dog which has had no fluid injected. By 

 comparing the strength of the two solutions the actual number of 

 milligrams present can be determined. Thus, if in 1 c. c. of the standard 

 solution there were 0.01 mg. and this gave a rise of 14 mm. of Hg, and 

 if 2 c. c. of a similar dilute solution of the unknown gave the same 

 rise, we would naturally argue that the second solution was one-half 

 the strength of the first and contained 0.005 mg. per c. c. The 

 solutions of the unknown can then be adjusted, so as to use the same 

 amount of fluid of the standard and the test controlled, reversing 

 the order of the injections. It is advisable to repeat the injections 

 several times, checking these results repeatedly. 



Elliott advises against using over 0.03 mg. Dale, using cats 

 according to Elliott's method, is said to measure epinephrin solu- 

 tions within about 5 per cent. 6 



Cameron, struck with the work of Marshall on the antagonism of 

 the members of the digitalis series with the nitrites, extended these 

 observations to the antagonism between the nitrites and adrenalin 

 and found that 0.6 mg. ( T ^ gr.) of nitroglycerin would require 

 0.0075 mg. of adrenalin to neutralize its vasodilator action in a rabbit 

 weighing 2,000 grams anaesthetized with ether. This method he 

 considers even more satisfactory than the simple blood pressure 

 measuring, especially if there is not a reliable standard preparation to 

 standardize against. One example from Cameron will illustrate. 

 The minimal effective dose of a 1 per cent solution was 0.5 c. c. The 

 minimal effective dose of an adrenalin solution had been found to be 

 0.00062 mg. for rabbits of 2,000 grains weight; hence, 0.005 c. c. of the 

 solution = 0.00062 mg. adrenalin, or 1 c. c. = 0.12 mg. By the nitrite 

 method 0.6 mg. is neutralized by 0.7 c. c. of 10 percent; this amount 

 of nitroglycerin is neutralized by 0.5 c. c. of 1.5 per cent adrenalin 

 solution (0.0075 mg.) ; therefore, 1 c. c. = 0.107 mg. This solution was 

 one-tenth stronger than adrenalin chlorid, 1-1,000. 



a Elliott, T. R. Action of adrenalin. Jour. Physiol., vol. 32, p. 448, 1905. 

 bBarger, G., and Ewins, A. J, Note on the molecular weight of epinephrin. Chem. 



News, vol. 93, p. 90, 1906. 

 c Cameron, I. D. On the methods of standardising suprarenal preparations. Proc. 



Roy. Soc. Edinburgh, vol. 26, p. 170, 1906. 



