ON THE EXPLANATION OF STANNIUS'S 

 EXPERIMENT AND ON THE ACTION OF 

 STRYCHNIA ON THE HEART. 



In conjunction with THEOD0P.E CASH, M.D. 



(Reprinted from SL Bartholomew'' s ILospital Reports, vol. xvi, 1880.) 



The remarkable experiment to which Stannius has given his 

 name consists in applying a ligature around the venous sinus of 

 tlie frog's heart, just at the point where it joins the auricles. The 

 consequence of tliis is, that the auricles and ventricles at once 

 cease to beat, and remain in a state of quiescence, lasting for a 

 time varying from a few minutes to half an hour or more, while 

 the venous sinus still continues to pulsate uninterruptedly. A 

 similar result is produced when, instead of applying a ligature 

 round the sinus, the sinus itself is separated from the auricles 

 by an incision. If, however, instead of suddenly removing the 

 whole of the venous sinus from the remainder of the heart, it 

 is gradually removed, the instant stoppage of the auricle and 

 ventricle does not take place. If the ventricle be now separated 

 from the auricle, while the two are remaining in a state of com- 

 plete quiescence, the ventricle again commences to pulsate, 

 while the auricle remains perfectly still. Two explanations of 

 these phenomena have been given. The one is that the section 

 or ligature of the heart at the junction of the venous sinus and 

 the auricles excites the inhibitory apparatus in the auricles ta 

 such an extent as to prevent both them and the ventricle from 

 moving. This explanation, however, seems to be disproved by 

 the fact that the same result is obtained after the heart has 

 been previously poisoned by atropia, wdiich completely paralyses 

 its inhibitory apparatus, and it would therefore appear that the 

 still-stand of the heart in this experiment cannot be due to 

 excitement of the inhibitory apparatus. The second explana- 

 tion is, that the motor ganglia of the heart are unequally 



