402 SIR THOMAS R. ERASER AND MR ALISTER T. MACKENZIE ON 



At 4.10 p.m., the heart was exposed. It was motionless and did not respond to 

 mechanical irritation. On section, the ventricular muscle was acid in reaction. 



In this experiment, the first three injections were quickly followed by a slight rise 

 in blood-pressure, which, however, was of brief duration. Immediately after the fourth 

 injection, the blood-pressure began to undergo rapid variations. At first, the oscillations 

 were almost regular in time and size (3.52.10) (fig. 9), but they soon became more 

 irregular in time and of larger size (fig. 11). Meanwhile, the average blood-pressure 

 fell, and in eight minutes after the injection it was almost zero (fig. 12). Thereafter, 

 the pressure rose again as general spasms occurred. 



The pulse-rate was almost unaffected until 6 minutes after the third dose (3.47.40) 

 (fig. 8), when it began to fall. After the fourth dose, a rapid fall in the pulse-rate 

 occurred, which became more marked as the oscillations in the blood-pressure increased 

 in irregularity (figs. 10, 11 and 12). The minimum pulse-rate was at 3.55.30, just 

 before the blood-pressure oscillations became very irregular, and at the time when the 

 average pulse movements were largest. 



The pulse movements were very slightly increased 10 minutes after the first 

 injection (3.35.10) (fig. 4). This increase was more noticeable 2 minutes after the 

 second dose (fig. 5). Six minutes after the third dose (3.47.40) (fig. 8), the increase in 

 the pulse movements was very distinct, coincident with the slowing of the rate. In 

 3^- minutes after the fourth dose, still larger pulse movements occurred (fig. 10), 

 accompanying a further slowing of the pulse-rate and the occurrence of rapid variations 

 in the level of the blood-pressure ; and the largest pulse movements of all were 

 coincident with a marked slowing in the pulse rate and the greatest irregularity of the 

 blood-pressure (figs. 11 and 12). 



The rate of the respirations was unaffected until after the fourth dose. The size of 

 the respiratory movements had diminished slightly before this time, and now marked 

 slowing of the respirations was accompanied by a considerable increase in their size. 

 At the end of the experiment, deep sighing respirations occurred, when the pulse-rate 

 became slowest and the blood-pressure very irregular. These were followed by a short 

 period of apnoea and then by respiratory convulsions. 



[Experiment LXXI. 



