588 DR THOMAS R. FRASER ON THE ANTAGONISM BETWEEN 



that terminated in recovery by dots, while the position assigned to each experi- 

 ment is determined by the doses of physostigma and atropia which were ad- 

 ministered. The doses of atropia are represented by the distance, in a 

 horizontal direction, from the perpendicular line forming the left margin of the 

 diagram, and increase at the rate of one-tenth of a grain for every two sub- 

 divisions of the horizontal lines. The doses of physostigma increase from 

 below upwards, — the minimum-lethal dose being represented by the red hori- 

 zontal line, a dose one and a half times as large as the minimum-lethal by the 

 black horizontal line immediately above the red line, a dose twice as large as 

 the minimum-lethal by the second black horizontal line, and so on until a line 

 is reached at the top of the diagram, which represents a dose of physostigma 

 four times as large as the minimum-lethal. The curved line, a be, separates 

 the fatal experiments (crosses) from those which terminated in recovery (dots) ; 

 and, accordingly, the blue space on the one side of it represents a region in 

 which death always occurs, and the pink space on the other side a region in 

 which recovery occurs. The doses that were given in any experiment within 

 each of these regions are readily ascertained from the position of the experi- 

 ment ; the dose of physostigma being determined by the horizontal line on 

 which the symbolic representation of the experiment is placed, and that of 

 atropia by the exact spot in the horizontal line which is occupied by the repre- 

 sentation. 



With these explanations, the results of the experiments will be rendered 

 apparent by a mere glance at the diagram. It may again be pointed out that 

 the more obvious of these results are, that the maximum dose of physostigma 

 which can be rendered non-lethal by atropia administered five minutes pre- 

 viously is about three and a half times the minimum-lethal dose, and that the 

 range of the doses of atropia which are able to render non-fatal various other- 

 wise fatal doses of physostigma, diminishes as the dose of physostigma increases. 

 The general nature of these results is well illustrated in the diagram by the 

 triangular form of the pink region of recovery after lethal doses of physostigma 

 (a b c), of which the apex indicates the maximum antagonisable dose of physo- 

 stigma, and the gradual increase in breadth from the apex to the red horizontal 

 line, the gradual increase in the range of doses of atropia that can prevent the 

 lethal effect of doses of physostigma diminishing from three and a half times 

 the minimum-lethal to the minimum-lethal. 



In this diagram, the pink region, and the curved line, a be, have been ex- 

 tended below the red line representing the minimum-lethal dose of physostigma, 

 and therefore into a space where the doses of physostigma are too small of 

 themselves to cause death. The lateral extension of the diagram, however, is 

 insufficient to exhibit the chief interest of this space ; but it will be pointed out 

 in the description of the next and only remaining group of experiments con- 

 nected with the present series. 



