ANTAGONISM IN ZYMOTIC DISEASES. 313 



all the more probable by the mutual antagonism of atroi)ia and 

 physostigma. Althougli this latter poison renders the vagus 

 very senrsitive, so that the power of any irritation applied to its 

 trunk to stop the heart is immensely increased, yet it has not 

 the extraordinary power of producing still-stand of the heart 

 possessed by muscaria. Unlike mrscaria, however, it has the 

 power of removing the paralysis of the vagus produced by 

 atropia, and, though an additional dose of atropia will again 

 cause paralysis, a second dose of physostigma will again remove 

 it. This difference of action between muscaria and pliyso- 

 stigma seems to show that they act on different nervous struc- 

 tures ; while the mutual power that atropia and physostigma 

 possess to neutralise each other's effects, indicates that atropia 

 acts on the same structure as physostigma, and consequently on 

 a different one from muscaria. 



Antagonism of Atropia and Physostigma. — Atropia and physo- 

 stigma are thus physiclogical antidotes to each other ; and 

 Fraser has shown that a dose of physostigma large enough to 

 kill an animal may be given to ic with impunity if atropia be 

 administered along with it, and that the animal may be after- 

 wards destroyed by a small dose given alone. It is true, 

 they do not completely counteract each other's action, each 

 one seeming to produce several effects, some of w^hich, and these 

 the most deadly, are neutralised by those of the other drug, 

 while others are not so neutralised ; and, if enormous doses be 

 administered, those active effects which are not neutralised may 

 become so powerful as to cause death, although they are com- 

 paratively unimportant when the dose is small. 



Importance of this in Therapeutics. — Nevertheless, within 

 certain limits these poisons do antagonise each other most suc- 

 cessfully ; and this observation seems to me to have a most 

 important bearing on the treatment of such diseases as have 

 thevr origin in morbid matter introduced into the system, for it 

 shows that it is not always necessary to eliminate a poison in 

 order to remove its effects, but that it may be neutralised and 

 rendered innocuous while still present in the organism ; and 

 seems to indicate that, for the treatment of zymotic diseases, w^e 

 should seek to discover such remedies as will counteract the 



