THE ACTIONS OF PHYSOSTIGMA AND ATROPIA. 533 



The recent development of the study of Pharmacology has led not only to 

 the acquisition of knowledge regarding the exact manner in which many active 

 substances influence the physiological conditions of vital structure, but also to 

 the differentiation of the special structures, by the modification of whose physio- 

 logical conditions the lethal action of these substances is produced. In a few 

 instances it has been shown that the nature of the modification produced in the 

 physiological condition of the structure or structures involved in the lethal action 

 of the substance is apparently contrary to that produced on the same structure 

 or structures by the physiological action of another substance. The estab- 

 lishment of such facts has led, within the last few years, to the suggestion of 

 two instances of antagonism, — the first being between the lethal action of prussic 

 acid and the physiological action of atropia, and the second between the lethal 

 action of muscaria and the physiological action of atropia. 



Between Atropia and Prussic Acid. — For the first of these instances Phar- 

 macological science is indebted to Professor Preyer of Jena. In the course of 

 an elaborate research* on the action of prussic acid, — a research that may 

 fairly be characterised as the most important that has yet been made on the 

 action of this substance, — Preyer established that the primary lethal action is 

 due to embarrassment of the respiratory and cardiac functions. He further 

 showed that the embarrassment of the former function is caused by stimulation 

 of the terminations of the vagi nerves in the lungs, and by impairment of the 

 activity of the respiratory nerve-centre, while the embarrassment of the latter 

 function is caused by excessive stimulation of the inhibitory cardiac fibres of 

 the vagi nerves. Previous investigators — more especially Von Bezold and 

 BixEBAUMt — had already shown that atropia produces effects that are in a 

 remarkable manner contrary to these ; for, in certain doses, it accelerates both 

 the respiratory and the cardiac movements, — the former, by paralysing the 

 terminations of the vagi nerves in the lungs, and by stimulating the respiratory 

 nerve-centre, and the latter, by paralysing the inhibitory cardiac fibres of the 

 vagi nerves. Guided by these facts, Preyer made a few experiments which 

 strongly support the opinion he has arrived at, that atropia is a physiological 

 antagonist to prussic acid, even to the extent of being able to prevent the primary 

 lethal action of that poison. It is, however, to be regretted that no attempt 

 was made absolutely to demonstrate that the dose of prussic acid used in each 

 experiment was a lethal one, more especially as the subsequently performed 

 experiments of Professor Bartholow — limited, no doubt, in their scope — do 

 not seem to confirm Preyer's opinion. % 



* Die Blausaure. Physiologisch Untersucht. Von W. Preyer, Dr. Med. et Phil. Bonn, 18 70. 

 I" Ueber die physiologischen Wirkungen des schwefelsauren Atropins. Von A. v. Bezold und Dr 

 Friedr. Blcebaum. (Untersuchungen aus dent physiologischen Laboratorium in Wurzburg. 1867.) 

 \ The Physiological Effects and Therapeutical Uses of Atropia and its Salts, 18G9, p. 25. 



VOL. XXVI. PART III. 6 Z 



