THE HEART-BEAT IN ITS PHYSIOLOGICAL RELATIONS 153 



after isolation have ceased beating, and if left to themselves in a 

 moist chamber do not develop rhythmical contractions, begin after 

 a while to beat when immersed in or irrigated with a solution of 

 sodium chloride or a solution of cane-sugar containing a little of that 

 salt. They refuse to beat in any solution which does not contain 

 sodium chloride (Lingle). The addition of calcium chloride to the 

 sodium chloride solution, or preliminary treatment of the strip with 

 a solution of a calcium salt before its immersion in the sodium 

 chloride solution, hastens the onset of the contractions, and increases 

 the length of time for which they are kept up (Erlanger). It is 

 unquestionable that for the normal beat of the heart the presence 

 of both salts is one of the necessary conditions, but there is at 

 present no sufficient foundation for the view that either the one or 

 the other acts as a special chemical excitant of the automatic 

 contraction. Still less necessary is it to make this assumption for 

 potassium. Certain potassium salts are, of course, beneficial to 

 the heart as to other tissues. This might be assumed from their 

 presence in blood and lymph, and it has been shown experi- 

 mentally. But a terrapin's heart will continue beating, and beating 

 well for a considerable time when irrigated with a solution con- 

 taining sodium and calcium salts alone and free from potassium. 

 That the reaction of the perfusive fluid is of great importance in 

 connection with the origination of rhythm is well established, and 

 it is an interesting fact that the limits of H ion concentration 

 within which the development of spontaneous beats is possible 

 differs for the hearts of different kinds of animals (Mines), and even 

 for the different portions of the frog's heart (Dale and Thacker). 

 While these facts illustrate the importance of the inorganic com- 

 position of the nutritive liquids for the action of the heart, they 

 leave the old question of the existence and the nature of an inner 

 stimulus to the rhythmic contraction very much where it was. 



Resuscitation of the Heart. Not only can the beat of the freshly- 

 excised mammalian heart be long maintained by artificial circulation, 

 but many hours or even some days after somatic death pulsation 

 may be restored by the perfusion of such a solution of inorganic 

 salts as Locke's through the coronary vessels. Kuliabko in this 

 way was able to restore a rabbit's heart which had been kept forty- 

 four hours in the ice-chest. Even after an interval of three to five 

 days from the death of the animal, in other experiments, pulsation 

 returned in certain parts of the heart, while twenty hours after 

 death from double pneumonia the heart of a boy three months 

 old was restored, and went on beating for over an hour. He obtained 

 also more or less complete restoration of the beat in the hearts of 

 persons dead from bronchitis combined with peritonitis or menin- 

 gitis, and from cholera infantum, but was unsuccessful in cases of 

 diphtheria complicated with septicaemia or erysipelas, and in cases 



