THE ACTIONS OF PHYSOSTIGMA AND ATROPIA. 617 



ship exists between the doses with which this mutual counteration occurs and 

 the length of the interval of time by which the administration of atropia pre- 

 cedes or follows that of physostigma. 



In presence of the many obvious proofs to the contrary contained in this 

 paper, I have considered it superfluous to enter into any discussion of the 

 possibility of this counteraction being the result either of some chemical 

 reaction between atropia and physostigma, or of an increased rapidity in the 

 elimination of the one substance produced by the action of the other. The 

 conditions of the experiments, and the symptoms that were observed, render it 

 certain that atropia prevents the fatal effect of a lethal dose of physostigma 

 by so influencing the functions of certain structures, as to prevent such modifi- 

 cations from being produced in them by physostigma as would result in death. 

 The one substance counteracts the action of the other ; and the result is a 

 physiological antagonism so remarkable and decided, that the fatal effect even 

 of three and a half times the minimum-lethal dose of physostigma may be pre- 

 vented by atropia. The existence of such an antagonism encourages the hope 

 that the power of directly counteracting disease is far from unattainable, and it 

 supplies a strong incentive to efforts designed to determine the conditions of 

 disease and the actions of remedies with an exactitude sufficient to show how 

 the remedial action may be applied as a counteracting influence to the diseased 

 condition. 



Explanation of Tabular Summary, <%c. — In the Tabular Summary of Experi- 

 ments, with which this paper ends, I have included only those experiments that 

 are mentioned in Section B, and have endeavoured to state the leading condi- 

 tions and symptoms of each experiment in as brief a manner as possible. The 

 time of occurrence of each symptom is computed from the moment when 

 the administration of the last-mentioned substance was commenced. It is 

 proper to explain, that in the column of effects on secretion and excretion, the 

 phrase "slight increase of secretion of certain buccal glands" implies merely 

 that such an increase was inferred from certain movements of the lips sug- 

 gestive of it ; and that the phrase in the same column " with atropia 

 none" implies merely that there was no evidence of any obvious effect ; but it 

 does not imply that diminution of secretion or excretion did not occur — for in 

 such experiments the occurrence of this effect could not without great difficulty 

 be certainly established. It will be observed that the size of the pupils is 

 always indicated by two measurements : the first mentioned being the size in a 

 perpendicular direction, and the second that in a horizontal one. 



I have not considered it necessary to mention the symptoms that were 

 observed in the o experiments (where a lethal dose of physostigma alone was 



VOL. XXVI. PART III. 7 X 



