THE ACTIONS OF PHYSOSTIGMA AND ATROPIA. 595 



Experiment 243. — With 3 grain of sulphate of atropia, death occurred. 

 Experiment 244. „ 0-5 „ „ death „ 



Kecovery, therefore, occurred in only one of the experiments in which atropia 

 was administered five minutes after a dose of physostigma three times as large 

 as the minimum-lethal. The administration of three twentieths and of one 

 fifth of a grain of sulphate of atropia resulted in death, but recovery took place 

 with the intermediate dose of four twenty-fifths of a grain. 



Experiments ivith Three and a half times the Minimum- Lethal Dose of Physo- 

 stigma. — The results of the previous experiments having made it obvious that 

 the largest dose of physostigma that can be rendered non-lethal by atropia 

 administered five minutes subsequently, is one three times as large as the 

 minimum-lethal, it was evidently unnecessary to perform many experiments 

 with a larger dose. Accordingly, only two such experiments were made, with 

 a dose three and a half times as large as the minimum-lethal;* and the chief 

 purposes of these experiments were to complete this portion of the series, and 

 to ascertain the nature of the phenomena that are produced when this dose of 

 physostigma is given five minutes before atropia. 



Experiment 245. — With 016 grain of sulphate of atropia, death occurred. • 

 Experiment 246. „ 0-2 „ „ death „ 



As both of these experiments terminated fatally, it was needless to continue 

 the series by making experiments with a larger dose of physostigma. 



The result of the whole series of experiments is therefore to show that 

 when atropia is administered five minutes after physostigma, the largest quan- 

 tity of the latter substance that can be rendered non-lethal by the former is 

 three times the minimum-lethal dose, and that the range of the doses of atropia 

 that are capable of preventing the lethal action of physostigma diminishes 

 according as the dose of physostigma is increased. 



The results of this series of experiments are illustrated in Diagram 3 (Plate 

 XXIII. ), which has been constructed on the same plan and scale as Diagram 1, 

 illustrating the first series of experiments, in order to facilitate a comparison 

 with it. It will be seen that the most prominent of the differences between 

 the two diagrams are, that the region of recovery after lethal doses of physo- 

 stigma (distinguished as a pink area enclosed within the curved line a b c, and 

 the segment a e of the red horizontal line) is smaller both in its perpendicular 

 and in its horizontal extent, and that the curved line a b c is much more 

 irregular in the diagram of the second series (Diagram 3) than in that of the 

 first (Diagram 1). 



The former of these differences very clearly illustrates the greater counter- 



* Tabular Summary, Series ii. Table 7. 



