1881.] in gland-celts hy means of osmic acid. 75 



are kept for some hours before being put in osmic acid suggests 

 that the staining of the normal tissue depends upon the presence 

 of some unstable constituent of the living protoplasm not at 

 present isolated. 



March 7, 1881. 



Professor Newton, President, in the Chair. 



The following communications were made to the Society : 



(1) On the Action of the Vagus Nerve upon the frog's heart. 

 By W. H. Gaskell, M.D., Trinity College. 



The chief object of this communication was to demonstrate by 

 means of curves certain effects of vagus stimulation as obtained by 

 a new method. 



The method used was the following : 



The heart was cut out, with vagus attached, the bulbus aortas 

 held tightly by means of Kronecker's forceps, the ventricle slit 

 open and the pxtreme apex attached by a thread to an ordinary 

 lever, so that the strip of cardiac tissue between the bulbus and 

 the apex alone moved the lever and recorded its movements on 

 the blackened drum. 



Also simultaneous tracings of the beats of the auricles and 

 ventricle and of the base and apex of the ventricle were obtained 

 by using an upper and lower lever and clamping, not too tightly, 

 the heart, either between the auricles and ventricle or midway 

 between the base and apex of the ventricle. The curves obtained 

 by these methods demonstrated the following facts : 



1. Weak stimulation of the vagus causes simply a marked 

 increase in the force of the contractions of the ventricle with, as a 

 rule, a slight acceleration in the rate of beat. 



2. Stronger stimulation causes a diminution in the force of 

 the contractions followed by an increase ; both during and after 

 the stimulation the rate of rhythm is frequently increased. 



3. When strong stimulation causes a complete standstill the 

 ventricular contractions increase in force and rapidity beyond the 

 normal after the stimulation has ended. 



4. The stimulation of the nerve may cause steady increase in 

 the force of the auricle contractions with simultaneous diminution 

 even to complete standstill of the ventricle contractions. After 

 the stimulation the increase in the ventricle contractions occurs 

 when the auricular have alrcadv begun to diminish. 



