DR THOMAS R. FRASER ON PHYSOSTIGMA AND ATROPIA. 713 



EXPLANATION OF PLATES XXIII. , XXIV., AND XXV. 



In each of the diagrams represented in these plates, the experiments that terminated in recovery 

 are marked by dots, and those that terminated in death by crosses ; and a line (distinguished in several 

 of the diagrams as a b c) has been drawn so as to separate the dots from the crosses. The area on 

 the side of the line where the dots occur bas been coloured pink, while the area on the side where 

 the crosses occur has been coloured blue ; and, accordingly, the pink area represents the region of 

 recovery, and the blue area the region of death. In the diagrams of Plates XXIII. and XXIV., the 

 red horizontal line indicates the position of the minimum-lethal dose of physostigma. 



Plate XXIII. 



Diagram 1 illustrates the first series of experiments, in which atropia in varying doses was administered 

 five minutes before varying doses of physostigma. 



Diagram 2 illustrates the small portion of the first series that extends to "2 gr. of sulphate of atropia. 

 It is drawn on a different scale from Diagram 1, as each tenth of a grain of sulphate of 

 atropia is indicated by twenty in place of by two subdivisions of the horizontal lines. 



Diagram 3 illustrates the second series of experiments, in which atropia in varying doses was adminis- 

 tered five minutes after varying doses of physostigma. 



Diagram 4 illustrates the small portion of the second series of experiments that extends to "2 gr. of 

 sulphate of atropia ; and the scale on which it has been drawn differs from that of 

 Diagram 3 to the same extent as the scale of Diagram 2 differs from that of Diagram 1. 



Diagrams 1 and 3 are mainly designed to illustrate the experiments extending from the minimum- 

 lethal dose of physostigma to the largest dose that can be counteracted successfully by atropia. They 

 have been drawn on the same scale in order that the results of the two series of experiments represented 

 by them may be compared. Diagrams 2 and 4 exhibit the course of the line a & in the first and second 

 series of experiments respectively, with greater distinctness and accuracy than Diagrams 1 and 3. 



Plate XXIV. 



Diagram 5 illustrates the first series of experiments ; but it differs from Diagrams 1 and 2 in so far that 

 the entire region of recovery (pink) is represented, and that each subdivision of the 

 horizontal lines indicates a tenth in place of a twentieth of a grain of sulphate of atropia. 

 The perpendicular red line marks the position of the minimum-lethal dose of sulphate of 

 atropia. 



The main purpose of this diagram is to show what combinations of atropia with less than the 

 minimum-lethal dose of physostigma are able to produce death. These combinations are represented 

 in the blue region below the red horizontal line. 



Plate XXV. 



Diagram 6 illustrates the third series of experiments, in which the dose of physostigma was constant 

 (one and a half times the minimum-lethal dose), while the dose of atropia and the in- 

 terval of time varied. In this diagram, as in Diagrams 1 and 3, each subdivision of the 

 horizontal lines represents one-twentieth of a grain of sulphate of atropia. The intervals 

 of time are represented by distance in a perpendicular direction from the thick horizontal 

 line, which indicates the zero interval or simultaneous administration ; and points below 

 this line indicate atropia administered after physostigma, while points above it indicate 

 atropia administered before physostigma. 



