36 



Dr. C. Bolton. Physiological Action of a [Mar. 20, 



Experiment 8. — Cat, weight 2920 grammes. Poison 1/10 gramme 

 (= - 034 gramme per kilogramme). 



Blood Pressure. — The blood pressure started to rise 20 seconds after the 

 injection, and went up from 170 mm. Hg to 194 mm. Hg. Then followed 

 the usual slight fall to 184 mm. Hg, and later a steady rise to a maximum 

 of 224 mm. Hg 120 seconds after the injection. From this point the 

 pressure steadily fell during the next 100 seconds to 30 mm. Hg. As the 

 blood pressure was declining (200 seconds after injection) the left vagus 

 was cut, but this procedure brought about no effect whatever upon the 

 blood pressure. The right vagus was cut 10 seconds later with a similar 

 result. 



Respirations. — Although there was no effect upon the blood pressure, yet 

 after both vagi had been divided typical vagus respiration ensued. 

 Inspiratory gasps were taken for five minutes after the blood pressure had 

 reached its lowest point. 



Heart Beats. — Before injection the frequency of the heart beats was 168 per 

 minute. Just before the final fall it was 270 per minute. 



Experiment 9. — Cat, weight 2130 grammes. Poison 1/20 gramme 

 (= 0"023 gramme per kilogramme). 



Blood Pressure. — The injection of the poison occupied 15 seconds, and the 

 blood pressure began to rise at the end of the eighth second. At the 

 end of 20 seconds the pressure had risen from 136 to 140 mm. Hg to 

 166 to 168 mm. Hg. During the next 25 seconds several sudden falls of 

 from 10 to 16 mm. Hg occurred. The pressure then became steady and 

 commenced to rise slowly. 



The right vagus was cut at this moment (54 seconds after the injection) 

 and 19 seconds later the left vagus was cut. These sections produced no 

 alteration in the steady rise of blood pressure, except such as were due to 

 the altered respiratory rhythm. 



The pressure reached its maximum point of 194 to 196 mm. Hg 

 131 seconds after the injection; it then commenced falling very rapidly, 

 and reached 40 mm. Hg above zero in 40 seconds (three minutes after the 

 injection). 



Heart Beats. — During the first rise of blood pressure the pulse rate 

 remained at 180 per second, the same as it was before the injection. During 

 the next period of the curve, when the falls in pressure were taking place, 

 the rate of the heart sank to 156 per minute. Later it became accelerated 

 again (about 228 per minute). The two sections did not materially 

 interfere with the frequency, which gradually increased up to 249 per 

 minute when the blood pressure reached its height. It maintained this 



