1883.] Chi the Motor Boots of the Brachial Plexus. §c. 229 



tricular nerves start, reflex movements of the animal (clog) were 

 observed. 



The reflex acceleration of the heart beat, to be obtained by central 

 stimulation of the cardiac nerves, is marked, and is not due to change 

 in blood pressure. The fact that sensory nerves go to the heart was 

 shown long ago by Ludwig and Cyon's discovery of the depressor 

 nerve in the rabbit. 



In the dog a large nerve (or two smaller) runs from the left vagus 

 ganglion and sometimes from the trunk, and ends chiefly between the 

 coats of the aorta, giving occasionally a branch to the Arteria 

 Pulmonalis. The peripheral stimulation of this nerve is without 

 effect. The central stimulation produces slowing of the heart and 

 fall of blood pressure ; sometimes the slowing is followed by accelera- 

 tion. The nerve is very sensitive to mechanical stimulation. 



The extent and importance of the centripetal nerves which come 

 from the heart and great vessels, is clearly shown in the author's 

 experiments. Whether the ventricular nerves are solely centripetal 

 or not has not been fully determined. It is rendered probable by the 

 author's experiments, that both vagus and accelerans act on 

 mechanisms in the auricles. In some cases the author has observed 

 changes of blood pressure follow stimulation of the peripheral ends of 

 nerves going direct to the heart, either without any change in the 

 beat, or without a corresponding change. But his observations on 

 this point are too few to draw definite conclusions. The mercurial 

 manometer was used. The dogs were narcetized with opium, and 

 then the brain divided through the pons, the object being- to render 

 the subsequent steps of opening the thorax painless,, and still to pre- 

 serve reflex actions. 



IV. " Note on the Motor Roots of the Brachial Plexus, and on 

 the Dilator Nerve of the Iris." By David Ferrier, M.D., 

 LL.D., F.R.S., Professor of Forensic Medicine in King's 

 College. Received April 24, 1883. 



In a communication to the Royal Society (published in the " Proc: 

 Roy. Soc," vol.32, 1881) on the "Functional Relations of the Motor 

 Roots of the Brachial and Lumbo- Sacral Plexuses," my colleague, 

 Professor Gerald Yeo, and myself gave an account of the results of 

 electrical stimulation of the several motor roots of the brachial and' 

 crural plexuses in the monkey. We there described the muscular- 

 actions of the upper extremity as resulting from stimulation of the 

 first dorsal up to the fourth cervical nerve. 



The careful dissections made at our request by Mr. W. Tyrell 

 Brooks, Demonstrator in the Physiological Laboratory, King's College, 



