THE ACTIONS OF PHYSOSTIGMA AND ATKOPIA. 571 



eyeballs had disappeared, while it was only with difficulty that now and again a 

 cardiac impulse could be detected. The gasping respiratory efforts became 

 gradually separated from each other by longer and longer intervals, until they 

 altogether ceased at twenty-two minutes after the commencement of the injec- 

 tion of physostigmia. 



After death, it was ascertained that the weight of the dog was ten pounds 

 and four ounces. 



It is shown by these experiments, that in dogs, as in rabbits, atropia exerts 

 a powerful counteracting influence to the lethal action of physostigma. It 

 would have been a matter of surprise had this result not been obtained, for there 

 was no reason to anticipate that either atropia or phyostigma would act other- 

 wise than in comformity with the general law, that every active substance 

 influences the same histological structures in the same way in whatever animal 

 these structures are present. No doubt the prominence and importance of the 

 results that are produced by essentially the same action vary somewhat in 

 different animals; but in judging of the probable existence of an antagonism 

 between two substances, the prominence or importance of an effect resulting 

 from any primary action is of secondary moment to the fact of the existence of 

 the action. Accordingly, if atropia be capable of producing upon one species 

 of animal an influence of such a nature as to antagonise in it the lethal action of 

 physostigma, it is difficult to imagine why it should not produce the same 

 antagonising influence in all animals of equally high development. The mere 

 fact of there being a difference in the lethal activity of atropia in different 

 animals, is not sufficient to lead to the supposition that it will not in them 

 successfully counteract the lethal action of physostigma; for the same primary 

 actions are produced, notwithstanding the differences that may exist in the 

 lethal activity. Many circumstances of a more or less accidental nature may 

 modify the lethal activity of poisonous substances, and among these is the 

 manner in which the substance is administered. In the case of atropia, its 

 lethal activity in rabbits may be enormously increased by introducing it directly 

 into a blood- vessal. 



Experiments in which Atropia ivas injected into a vein and Physostigma 

 under the skin.— It seemed therefore of importance to administer atropia by 

 injection into a vein, in order to determine whether, when so administered, it 

 still, notwithstanding the great increase that is thus produced in its lethal 

 activity, retains the power to counteract the lethal action of physostigma. 



Experiment 55-a. — A rabbit, weighing four pounds, was secured by means 

 of a Czermak's rabbit-holder, and one of the external facial veins was exposed, 

 and two ligatures were loosely applied to a small portion of it dissected from 

 its connections. Two grains of extract of physostigma was then administered 

 to the rabbit by subcutaneous injection. 



