CARL LUDWIG. 169 



ago Cyon left St. Petersburg, and devoted himself to 

 journalistic work in Paris. 



Purposely not taking Ludwig's discoveries in chrono- 

 logical order, let us turn for a moment to another nerve in 

 connection with the heart, whose action he discovered, viz., 

 the nerve which from its action he called "Accelerans 

 Cordis ". This nerve passes from the upper dorsal region 

 of the spinal cord to the heart, and when it is divided and 

 its peripheral end stimulated, it causes a great accelera- 

 tion in the number of heart beats, hence the name given to 

 it by Ludwig and Baxt. In this country it is also called 

 Augmentor cordis. Naturally, Ludwig compared the effect 

 of the vagus on the heart, discovered by his predecessor E. H. 

 Weber, with that of the accelerans. The vagus or its 

 inferior cardiac branch when stimulated slows or may 

 even arrest the action of the heart in the relaxed or 

 diastolic phase for a few seconds. On comparing the 

 results obtained by simultaneous stimulation of these two 

 nerves, Ludwig and Baxt came to the conclusion that they 

 do not act on the same intracardiac mechanism. 



But while the Kymograph enabled Ludwig and his 

 pupils to discover numerous important facts relative to the 

 action of the heart, it primarily put one in possession of 

 facts which led to an entirely new conception of the 

 activity of the blood-vessels or at least the action of the 

 nervous system thereon. Ludwig and Thiry, in 1864, 

 showed the influence of the cervical spinal cord on the 

 blood stream, dwelling particularly on the fact that the 

 varying and variable capacity of the portal, i.e., abdominal, 

 area was largely concerned in the regulation of the blood 

 pressure in the branches of the aorta, a fact which fits in 

 well with the subsequent discovery of the depressor nerve. 



In the medulla oblongata or bulb, Ludwig and his 

 pupils, Owsjannikow and C. Dittmar, succeeded in deter- 

 mining accurately the position of the so-called chief vaso- 

 motor centre, i.e., a part of the nervous system from which 

 impulses are continually proceeding to the smooth muscular 

 fibres, more especially of the small arteries or arterioles, 

 whereby these muscular fibres are kept in a state of partial 



