428 TEXT-BOOK OF PHYSIOLOGY. 



The Traube-Hering Waves. Under certain experimental conditions 

 the arterial blood-pressure tracing exhibits, in addition to the usual respira- 

 tory variations, certain longer rhythmic variations more or less wave-like in 

 character, which are known as Traube-Hering waves. They can be devel- 

 oped on a blood-pressure tracing by injecting magnesium sulphate or mor- 

 phine into the circulation, by tying the cerebral arteries, etc. These waves 

 indicate a periodic contraction and dilatation of the blood-vessels, the result 

 of a stimulation of the vaso-motor centers. 



