530 DR THOMAS R. FRASER ON THE ANTAGONISM BETWEEN 



Physiological Antagonism. 



Localised Antagonism. — In order perfectly to neutralise the effects that 

 follow the introduction of a poison into the living economy, it would appear to 

 be necessary that the physiological functions of the affected organism should be 

 modified. The early, though, undoubtedly, crude notions that originated the 

 employment of alexipharmics, Mithridates, and theriacse, to a certain extent 

 recognised this principle. The more perfect knowledge acquired within recent 

 times regarding the functions of structures and organs, has led. to the discovery 

 that various substances are able to modify them in a definite and constant 

 manner, and that the modifications produced by certain substances are of a 

 nature contrary or opposite to that of those produced by others. By such obser- 

 vations, the existence of physiological antagonism between certain of the effects 

 of different active substances has been demonstrated. Several apparently well- 

 authenticated examples have been made known : among which may be instanced 

 the antagonism between the actions on the iris and on the minute blood-vessels, 

 of opium or morphia on the one hand, and belladonna, hyoscyamus, and 

 stramonium on the other ; between the actions on the capillary circulation of 

 morphia and quinia ; between the actions on the vagi nerves of physostigma 

 and atropia, hydrocyanic acid and atropia, and muscaria and atropia ; and 

 between the actions on the iris and on visual accommodation of physostigma 

 and atropia. 



General and Lethal Antagonism. — In some instances, the existence of such 

 limited counteractions has led to the supposition that the general, or, at least, 

 the primary lethal action of one of the substances concerned is capable of 

 being antagonised by the physiological action of the other. A notable instance 

 of this is to be found in the revival, by the late Dr Thomas Anderson, in 1854, 

 of the old, but, at that time, almost forgotten doctrine, that belladonna is a 

 physiological antidote to the poisonous action of opium.* Anderson was led to 

 this idea from the fact that these two substances produced contrary effects on 

 the iris. The occurrence of an antagonism limited to a single organ in no 

 important degree related to the continuance of life is, however, an insufficient 

 reason for supposing that the general actions of any two substances are of an 

 antagonistic nature. In order legitimately to infer whether one substance is 

 capable of acting as a physiological antidote to another, it is necessary to acquire 

 a definite knowledge of the exact nature of the general physiological action 

 exerted by each of them. As yet the action of only a few substances has been 

 ascertained with the completeness that is required ; and hence it is that the 

 examples that have been advanced of general antagonism between the actions 



* Edinburgh Medical and Surgical Journal, vol. xviii. 1854, p. 377. 



