76 Mr W. H. Gaskell, On the Action of the Vagus Nerve. [Mar. 7, 



5. When the ventricle is beating alternately weakly and 

 strongly, stimulation of the nerve makes all the beats equally 

 strong. 



6. This alternation of beats may occur in the apex of the 

 ventricle alone while the base beats regularly, and then the vagus 

 stimulation causes the apex beats to become equally strong. 



Further by the method used the action of poisons, such as 

 Atropin, Muscarin, Digitalin, on different parts of the heart and 

 on the effect of the vagus nerve was demonstrated, and it was 

 shewn that : 



1. When the beats of the heart were reduced in size as by 

 the application of normal saline solution, then Atropin Sulphate 

 1 p. c. solution applied to the heart caused an increase in the 

 force of the contractions with a slower rhythm. 



2. Atropin applied to the heart caused a slower rhythm with 

 strong contractions and removed all the various effects of vagus 

 stimulation. 



3. Atropin applied to the ventricle only did not prevent the 

 action of the nerve on the ventricle. 



4. Atropin applied to the auricles and sinus only removed 

 the whole effect of the nerve from all parts of the heart. 



5. Muscarin applied to the ventricle only reduced the size of 

 its contractions and relaxed the tissue without altering the rhythm, 

 at all events at first, and without affecting the auricles in the least. 



6. When after the application of Muscarin or Digitalin the 

 ventricle had ceased beating in a relaxed or semi-contracted con- 

 dition respectively, then Atropin in each case brought back the 

 beats without altering the condition of the tissue. 



The author suggested from the consideration of these and 

 many other curves which he possessed, that a possible explanation 

 of the action of the vagus might be found on the hypothesis that 

 the vagus is the trophic nerve of the cardiac muscle. He however 

 could not at that stage of his investigation give any definite 

 explanation of the phenomena observed by him, but trusted that 

 further experiments would enable him to do so. 



(2) On the ancestral form of the Chordata. By F. M. Balfour, 

 M.A., F.R.S., Fellow of Trinity College. 



