616 DR THOMAS R. ERASER ON THE ANTAGONISM BETWEEN 



sufficient number of such curves, however, the labour and expenditure of time 

 would be very great, seeing that so large a number of experiments as two 

 hundred and seventy-six were made in order to obtain the curves represented 

 in the diagram. Besides, a tolerably accurate conception of the form of the 

 curved surface may be gained from the curves of the three series of experiments 

 that have been made. 



In all probability the summit of this curved surface does not occupy an 

 elevation materially above that of the apex of the curve a a' ; but if it reach a 

 higher elevation, the highest point will probably be situated at only a short 

 distance behind that apex. From the highest point the surface slopes gradually 

 to d c, somewhat steeply to a' b', with decided steepness to b' b, and with still 

 greater steepness to b a. 



The region included within this curved surface represents every possible 

 variation in the doses of atropia and physostigma and in the intervals of time 

 separating the administration of the two substances that is compatible with the 

 production of successful antagonism between physostigma and atropia. 



General Summary. — Although the above combined representation of the 

 three series of experiments in reality presents a complete summary of the more 

 important of the results that have been obtained, it may be convenient to briefly 

 recapitulate these results. At page 540, I have stated that the chief objects of 

 the research are to show that atropia possesses in a remarkable degree the 

 power of counteracting the lethal action of physostigma, and to examine the 

 extent of this power and define its limits. 



The former object has been effected by a detailed account in Section A of 

 several experiments in which the fatal action of a dose of physostigma equal to 

 or greater than the minimum-lethal was prevented by the physiological action 

 of a non-lethal dose of atropia, as well as by a brief account in Section B, of 

 a larger number of similar experiments, which, however, are also described 

 with greater detail in the Tabular Summary. The total number of these ex- 

 periments is one hundred and sixty one ; and in each of them the animal used 

 was killed many days afterwards, and when the effects of the two substances 

 had completely disappeared, by a dose of physostigma less than or only equal 

 to that from which it had previously recovered. 



The examination of the extent of the counteracting influence of atropia upon 

 the lethal action of physostigma, as well as the defining of the limits of this 

 influence have been accomplished in the manner and with the results fully 

 described in Section B. By means of the three series of experiments contained 

 in this section, it has been ascertained what is the maximum dose of physo- 

 stigma that can be counteracted successfully by atropia, what are the doses of 

 atropia that can counteract any given dose of physostigma, and what relation- 



