Death and Dissolution of the Organism 357 



effect of the lack of oxygen upon the heart-beat of the em- 

 bryo of the same fish Ctenolabrus. This egg is perfectly 

 transparent and the heart-beat can easily be watched. 

 When these eggs are put into an Engelmann gas chamber 

 and a current of pure hydrogen is sent through, the heart 

 may cease to beat in fifteen or twenty minutes; it stops 

 beating suddenly, before the number of heart-beats has 

 diminished noticeably, and ceases beating before all the 

 free oxygen can have had time to diffuse from the egg. 

 In one case the heart beat ninety times per minute before 

 the hydrogen was sent through; four minutes after the 

 current of hydrogen had passed through the gas chamber, 

 the rate of the heart-beat was eighty-seven per minute, 

 three minutes later it was seventy-seven, and then the 

 beats stopped suddenly. It is hard to believe that this 

 cessation could have been caused by lack of energy. 

 Hydrolytic processes alone could furnish sufficient energy to 

 maintain the heart-beat for some time, even if all the oxygen 

 had been used up. The suddenness of the standstill at a 

 time when the rate had hardly diminished seems to be 

 more easily explained by a sudden collapse of the machine; 

 it might be that liquefaction or some other change of 

 structure occurs in the heart or its ganglion cells, compar- 

 able to that which we mentioned before. In another fish 

 Fundulus^ where the cleavage cells undergo no visible 

 changes in the case of lack of oxygen, the heart of the em- 

 bryo can continue to beat for about twelve hours in a cur- 

 rent of hydrogen. In this case the rate of the heart-beat 

 sinks during the first hour in the hydrogen current from 

 about one hundred to twent}'' or ten per minute; then it 

 continues to beat at this rate for ten hours or more. In 

 this case one might believe that during the period of steady 

 diminution of the tension of oxygen in the heart (during 

 the first hour), the heart-beat sinks steadily while it keeps 

 up at a low but steady rate as long as the energy for the 



