1885.] TROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 101 



ON THE INFLUENCE OF ATROPIA ON THE HEART. 



By Dr. H, G. BEYER, IT. $4. N., 



Honorary Curator, Section of Materia Medica, U. S. Naiional Museum. 



Last winter, while engaged iu studying tlie physiological action of 

 atropia on the heart, I found among the manj^ terrapins I had occasion 

 to use one whose heart was in a peculiarly abnormal condition. The 

 auricles were very large, larger in fact than the ventricle in diastole, and 

 although contracting in rythmical sequence with relation to the ventric- 

 ular systole, their contraction was barely perceptible, while the ven- 

 tricle performed its work iu a most satisfactory manner; that is to say, 

 an attempt at contraction on the the part of the auricles was immediately 

 followed by the ventricular systole. I determined, however, to proceed 

 to isolate it in. the usual manner and begin observations on it with 

 atropia. 



After the operation of inserting the inflow cannulas into the respect- 

 ive veins, and the outflow cannulas into the arteries, on allowing the 

 nutrient blood-mixture to flow through the heart, no change in its con- 

 dition was noticed. No lowering of the venous pressure would make 

 the least difference, and even a venous pressure of only 0.5'''" was still 

 sufficient to keep the auricles in their distended condition. 



Hoping, nevertheless, to induce the auricles to perform their normal 

 work, well oxygenated fresh nutrient blood-mixture was allowed to run 

 through it for over two hours but still the condition remained unaltered. 



A back flow of blood from the auricles into the venous cannulas and 

 inflow tubes could be plainly seen to occur with each ventricular systole, 

 showing the undoubted existence of a free and direct communication 

 between ventricle and auricles and auricles and veins. Their respect- 

 ive valves, therefore, were clearly insufficient from the distended con- 

 dition of the auricles. All the more surprising was the change which 

 occurred when atropized blood was substituted for the normal nutrient 

 blood-mixture, as the following record of the experiment will show. 



The heart under observation, being clearly an abnormal one, and 

 therefore not to be found in every terrapin, though it might perhaps be 

 artificially produced without serious injury to the organ, I nevertheless, 

 determined not to publish it until an opportunity ofiered itself for veri- 

 fying the results attained. 



I was fortunate enough to open a terrapin last January which pre- 

 sented a heart in a similar, if not identical, condition, and it was at once 

 concluded to try atropia with the result of inducing the inactive auri- 

 cles to perform their work and thus increase the entire amount of work 

 done by the heart from 100 to 150 per cent. 



Inasmuch as these two experiments are strikingly well calculated 

 to throw important light on the stimulating influence exerted by atropin 



