538 
Proceedings of the Royal Society 
(4.) Nitrogen and aqueous vapour passed over sodium yielded no 
ammonia. The reason for this was said to be that a nitride of 
sodium does not exist. The real reason for the non-formation of 
ammonia appeared to be due to the violent action of the aqueous 
vapour on the sodium. If sodium amalgam were used in order to 
modify the action of the sodium, we believe that ammonia would 
be produced. It is our intention to try this experiment. 
[A discussion followed the reading of this paper, in which Pro- 
fessor Crum Brown, Mr Dewar, and Mr Catton, took part.] 
Monday , ?>d May 1869. 
Dr CHEISTISON, President, in the Chair. 
The following Communications were read : — 
1. Influence of the Vagus upon the Vascular System. By 
William Butherford, M.D., F.E.S.E., Demonstrator of 
Practical Physiology in the University of Edinburgh. 
Abstract. 
The author gave the chief results of 120 experiments upon frogs, 
rabbits, and dogs, as follows : — 
1. He showed, by novel methods of experimentation, that the 
inferior cardiac branches of the vagi are — as the brothers Weber 
pointed out — inhibitory nerves of the heart, and that they cannot 
in any sense be regarded as motor nerves of the heart, as maintained 
by Schiff, Moleschott, Lister, and others. The experiments bear- 
ing on this question were performed in 1866-67. 
2. Because the heart usually beats more rapidly after division 
of the vagi, Von Bezold and others have concluded that the 
vagus is continually restraining the heart’s movements. The 
author showed that increase of the blood pressure is generally the 
cause of the quickened cardiac action after division of the vagi, 
a fact which had been overlooked by all previous observers. Von 
Bezold’s theory, that the vagi continually inhibit the heart, was 
therefore shown to be devoid of the necessary proof. 
