THE ACTIONS OF PHYSOSTIGMA AND ATEOPIA. 



591 



occurs somewhat abruptly at the intersection of the red horizontal line, repre- 

 senting the minimum-lethal dose of physostigma; and it very graphically 

 represents some of the results to which attention has been drawn in the 

 description of the experiments. It was shown by these experiments, that when 

 physostigma is administered in lethal doses, the range of the doses of atropia that 

 are able to produce successful counteraction increases by about one grain for 

 each successive decrease by half the minimum-lethal dose in the dose of physo- 

 stigma. When, however, physostigma is administered in a dose equivalent only 

 to half the minimum-lethal, the range of doses of atropia that may be given with- 

 out the occurrence of death is increased beyond the range for the minimum-lethal 

 dose, not by one grain only, but by four grains and three-tenths. Accordingly, 

 while in the region where the doses of physostigma are lethal, the line separating 

 the area of death from that of recovery possesses a direction which indicates 

 an increase of one grain of sulphate of atropia for each decrease by half the 

 minimum-lethal dose in the quantity of physostigma, in the region where the 

 dose of physostigma is less than lethal, it possesses a direction which indicates 

 an increase of about four grains and a half of sulphate of atropia for each 

 decrease by half the minimum-lethal dose in the quantity of physostigma. 



II. Determination of the Limits of Antagonism when Atropia is 

 Administered Five minutes after Physostigma. 



The second series of experiments was undertaken to determine the limits of 

 successful antagonism when atropia is administered five minutes after physo- 

 stigma. In the experiments of this series, physostigma was administered in 

 the form of sulphate of the active principle ; of which preparation it has already 

 been shown that the minimum-lethal dose is about 012 grain per three pounds 

 weight of rabbit. As this dose is the one-tenth of the minimum-lethal dose of 

 extract of physostigma, the experiments of the first series may readily be com- 

 pared with those of the present. 



Experiments with the Minimum- Lethal Dose of Physostigma. — When the 

 minimum-lethal dose of sulphate of physostigmia was administered five minutes 

 before various doses of sulphate of atropia, the results were as follows : — * 



Experiment 168. — With 01 grain of sulphate of atropia, death occurred. 



Experiment 169. 

 Experiment 170-a. 

 Experiment 171-a. 

 Experiment 172-a. 

 Experiment 173-a. 



0015 



0-02 



005 



01 



02 



death 



recovery 



recovery 



recovery 



recovery 



* Tabular Summary, Series ii. Table 2. 



