THE ACTIONS OF PHYSOSTIGMA AND ATROPIA. 605 



ful counteraction. The smallest of these doses of sulphate of atropia is exactly 

 the same as that which can successfully counteract one and a half times the 

 minimum-lethal dose of extract. The largest, however, is smaller by two fifths 

 of a grain than the largest close that can successfully counteract one and a half 

 times the minimum-lethal dose of the extract ; and this difference, as tending 

 to show that the dose of sulphate of physostigmia adopted as the minimum- 

 lethal is somewhat more powerful than the dose of extract adopted as such, 

 confirms the result of the experiments by which the minimum-lethal dose of 

 these two preparations of physostigma was determined. 



In the description of the other experiments of this group, those performed 

 with each of the doses of sulphate of atropia administered will be separately 

 considered, commencing with the smallest dose that was given. The experi- 

 ments made with each dose of sulphate of atropia will be briefly described in 

 an order proceeding from the shortest to the longest interval of time that 

 separated the administration of the two substances. In the account of these 

 experiments, the interval of time, the dose of sulphate of atropia, and the result 

 of the experiments, will alone be mentioned. 



The smallest dose of sulphate of atropia that was given at various intervals 

 before one and a half times the minimum-lethal dose of sulphate of physo- 

 stigmia, was one twentieth of a grain (0'05 gr.) ; and with this dose the follow- 

 ing experiments were performed : — 



Experiment 290-a. — With an interval of 10 minutes, recovery occurred. 

 Experiment 291-a. ,, 15 „ recovery „ 



Experiment 292-a. „ 20 „ recovery „ 



Experiment 293. „ 25 „ death „ 



Experiment 294. „ 30 „ death „ 



These experiments show that the administration of one twentieth of a grain 

 of sulphate of atropia may precede that of one and a half times the minimum- 

 lethal dose of physostigma by an interval of twenty minutes, or less, and still 

 successful antagonism will occur. If, however, this interval be prolonged 

 beyond twenty minutes, as to twenty-five or thirty minutes, successful anta- 

 gonism does not occur. 



In the next experiments, the dose of sulphate of atropia was half a grain 

 (0"5 gr.) ; and the intervals that elapsed between its administration and the 

 subsequent administration of one and a half times the minimum-lethal dose of 

 physostigma, as well as the results of the experiments, were as follows : — 



Experiment 295-a. — With an interval of 15 minutes, recovery occurred. 

 Experiment 296-a. ,, 25 „ recovery „ 



Experiment 297-a. .„ 30 „ recovery „ 



VOL. XXVI. PART III. 7S 



