PHYSIOLOGICAL ANTAGONISM 145 



mitigate or arrest its effects. When a lethal dose has been 

 swallowed, endeavour should be made, before it has time to 

 enter the circulation, promptly to remove it by the stomach- 

 pump, stomach syphon, or by an emetic. It is advisable, 

 however, in all cases to empty the stomach, and thus remove 

 unabsorbed portions of the poison, before giving any fluid 

 which favours solution and absorption, or even before ad- 

 ministering the antidote. Some antidotes, such as charcoal, 

 and demulcents, mechanically envelop the particles of the 

 poison, or ensheath and protect the mucous surfaces, and 

 thus retard absorption. Many enter into chemical combina- 

 tion with the poison, forming comparatively insoluble inert 

 compounds (chemical antidotes). Thus, albumin forms, 

 with corrosive sublimate and other metallic salts, insoluble 

 albuminates. Freshly precipitated ferric oxide converts 

 arsenious acid into an insoluble iron arsenite. When poison 

 has been introduced into a wound, as by the bite of a rabid 

 dog, or by the fang of a serpent, a ligature, if possible, is 

 placed so as to prevent or retard absorption, and the wound 

 is forthwith thoroughly washed with antiseptics and 

 cauterised or excised. 



The action of poisons, even after absorption, may, more- 

 over, be controlled and counteracted by remedies which 

 antagonise their lethal tendencies (physiological antidotes). 

 Hypodermic injection of anti venomous serum neutralises the 

 poison of cobra. Opium lessens the irritation and pain 

 caused by irritants. Artificial respiration frequently sus- 

 tains life throughout the stage of deadly narcosis induced by 

 curare, prussic acid, or anaesthetics. But still more definite 

 antagonism occurs between certain drugs. The stimulant 

 and convulsant effects of strychnine on the spinal cord 

 are opposed by chloral hydrate and tobacco, which lessen 

 the excitability of the cord. The fatal depression of the 

 cardiac and respiratory centres, produced by large doses 

 of aconite, is antagonised by alcohol, atropine, digitalin, 

 and by strychnine. Between pilocarpine and atropine 

 the antagonism is very marked in their actions on the 

 vagus, heart, muscular tissues, and iris, as well as on 

 secretion. 



Two explanations are given of this antagonism (1) By 



