610 DR THOMAS R. ERASER ON THE ANTAGONISM BETWEEN 



to that line, represents five minutes ; and each of those of distance to the right 

 from the perpendicular line forming the left margin of the diagram, which are 

 marked out by the lines drawn parallel to that line, represents (as in Diagrams 

 1 and 3) a twentieth of a grain of sulphate of atropia. The constant dose of 

 physostigma was one and a half times the minimum-lethal one. 



The conditions of each experiment may, therefore, at once be apprehended 

 from the position occupied by the representation of the experiment in the 

 diagram : whether atropia was administered before or after physostigma is 

 seen from the representation of the experiment being placed above or below 

 the zero line ; what the interval of time separating the administration of the 

 two substances was, from the distance of this representation in a perpendicular 

 direction from the zero line of time ; and what dose of sulphate of atropia was 

 administered, from the distance of this representation in a horizontal direction 

 from the left margin of the diagram. 



In this diagram, as in the others as yet described, the experiments that ter- 

 minated in recovery (dots) have been separated from those that terminated in 

 death (crosses) by a black line ; and the regions of recovery and death that are 

 thereby mapped out have been coloured respectively pink and blue. 



When the diagram is examined, the two points to which attention will pro- 

 bably be attracted first are the irregular form of the region of recovery (pink), 

 and the much greater extent, both horizontal and perpendicular, of the portion 

 of this region where atropia was administered before physostigma than of the 

 portion where atropia was administered after physostigma. The existence of 

 this difference illustrates very distinctly a general result of the experiments of 

 this series, namely, that successful antagonism occurs with a greater range of 

 doses of atropia and with a greater range of intervals of time between the two 

 administrations, when atropia is given before physostigma, than when it is given 

 after it. In the latter case, the length of the intervals of time is obviously 

 limited by there being a limitation to the time within which this dose of physo- 

 stigma itself produces death. In the former case, the intervals are not subject 

 to a similar curtailment, seeing that the doses of atropia represented in the 

 diagram are all considerably below the minimum-lethal dose. 



In reference to the irregularity in the form of the region of recovery, the 

 only special point to which attention need be drawn, is the existence of the 

 curious anomaly in the portion where atropia was administered after physo- 

 stigma. This anomaly brings into almost too great prominence the fact, already 

 at some length considered, that the maximum dose of atropia that produces 

 successful antagonism with the dose of physostigma employed in this series was 

 found to be greater when the latter substance is administered ten minutes 

 before the atropia than when it is administered only five minutes before it. It 

 has already been shown that the existence of this seemingly anomalous result is 



