220 CIRCULATION. 



artificial respiration, in drowning, etc., particularly by what 

 is known as the Marshall Hall method, are evidence of this 

 fact. In cases of asphyxia, those measures by which artificial 

 respiration is most effectually maintained have been found 

 most efficient. 



Certain individuals have the power of temporarily arrest- 

 ing the action of the heart by a voluntary suspension of res- 

 piration. The most remarkable case of this kind on record 

 is that of Colonel Townshend, which is quoted in many 

 works on physiology. 1 Col. T. was said to be able to arrest 

 respiration and the action of the heart so completely as to 

 simulate death. When in this condition, the pulse was not 

 perceptible at the wrist nor over the praecordia, a mirror held 

 before the mouth was not tarnished, and he was to all ap- 

 pearances dead. On one occasion, in the presence of several 

 medical gentlemen, he remained in this condition for half an 

 hour ; afterwards the functions of respiration and circulation 

 becoming gradually reestablished. This, to say the least, is a 

 very remarkable case, but is credited by many physiologists. 



Cause of the Rhythmical Contractions of the Heart. 



The phenomena attending the action of the heart pre- 

 sent few difficulties in their investigation, compared with the 

 study of the cause of the regular contractions and relaxations, 

 which commence early in foetal development, to terminate 

 only with life. This interesting question has long engaged 

 the attention of physiologists, and has been the subject of 

 numerous experiments and speculations. It would be idle 

 to follow the various theories which have been offered to 

 account for this constant movement, except as a subject of 

 purely historical interest ; for many of them are based upon 

 a very imperfect knowledge of the phenomena of the circu- 



1 DUXGLISON, Human Physiology, Philadelphia, 1856. Eighth edition, vol. i., 

 p. 405. 



