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XXI. — An Experimental Research on the Antagonism betiveen the Actions of 

 Physostigma and Atropia. By Thomas R. Fraser, M.D., Lecturer on 

 Materia Medica and Therapeutics at Surgeon's Hall, Edinburgh. (Plates 

 XXIII. to XXV.) 



(Read 29th May 1871.) 



INTRODUCTION. 



It is natural to suppose that soon after it became known that injurious 

 effects follow the introduction of certain substances into the system, attempts 

 were made to remedy these effects, and also to discover counteragents, or 

 antidotes, to the hurtful substances. The success attending these attempts must, 

 of necessity, have been closely related to the existing state of knowledge regard- 

 ing the actions of active substances. When the effects of poisons were referred 

 to supernatural manifestations, it was chiefly charms and superstitious rites that 

 were trusted to as protectives and remedies. At a somewhat more advanced 

 period in the progress of human knowledge, vague notions of physiological laws 

 and processes supplied the indications of curative treatment. Alexipharmics, 

 Mithridates, and theriacae were compounded of substances possessing elimina- 

 tive and so-called " general stimulant " properties, and bezoars of such as 

 enjoyed a reputation as specifics against poisonous influences ; and these were 

 employed, almost indiscriminately, as universal antidotes. Still later, chemistry 

 suggested that, as the physical properties of poisons may be modified by various 

 re-agents, so may their effects be prevented by the administration of suitable 

 substances. 



The recommendations derived from chemistry were at first only of the crudest 

 description ; but as the science advanced, many valuable hints were obtained, 

 and now the class of the chemical antidotes probably includes the largest 

 number of efficient counteragents to poisons. Alkalies and acids are employed 

 to neutralise each other, tannin to render insoluble tartar emetic and many vege- 

 table alkaloids, hydrated sesquioxide of iron to precipitate arsenious acid, and 

 soluble and inert sulphates to decompose lead salts, and render them unabsorb- 

 able. In these examples, as well as in the many others belonging to this class, 

 the operation of the antidote is limited to the chemical change it produces on 

 the poison while it remains in the alimentary canal. As soon as the poison 

 becomes absorbed into the blood, it appears to pass beyond the antidota] 

 influence of the chemical counterpoison, for no example exists of a chemical 

 antidote neutralising a poison after absorption. Thus it is that the value of 

 such antidotes is considerably restricted. 



VOL. XXVI. PART III. 6 Y 



