248 PROTEIN POISONS 



constant result of the reinjection. When sensitization is 

 not complete, fall in .pressure may be the only symptom. 

 In all cases there is complete parallelism between the 

 clinical symptoms and the fall in blood pressure. As the 

 latter proceeds the former increase in intensity, and in 

 recovery rise in pressure accompanies the return to the 

 normal. With a normal pressure of from 120 to 150 mm. 

 of mercury, soon after the reinjection, and as the pulse 

 grows smaller and faster and the general depression deepens, 

 the blood-pressure in the femoral artery falls to 80 or 60, 

 sometimes to 40 or even less. The character of the curve 

 changes, the effects of respiratory movements become less 

 marked, and cease altogether as the pressure approaches 

 the low y est point. Now, only the movements of retching 

 and expiratory spasms cause transitory rises in the curve. 

 When the lowest point is reached the depression is greatest 

 and recovery is indicated by and accompanies rise in 

 pressure. The corneal and cutaneous reflexes remain 

 intact throughout, and exclude both a central narcosis and 

 peripheral muscular paralysis. The absence of marked 

 respiratory disturbances is an additional indication in the 

 same direction, and, furthermore, shows that the respiratory 

 function of the red corpuscles is not at fault. 



The genesis of the fall in blood pressure becomes an 

 interesting question. The type of the fall and the accom- 

 panying condition of the pulse show that it is not due to 

 weakness of the heart's action. More than fifty years ago 

 it was shown by Marey that a fall in blood-pressure accom- 

 panied by increased frequency of the pulse is not due to a 

 decrease in the strength of the heart, but in all probability 

 to. decreased peripheral resistance. Both in the course of 

 the fall and after it has reached the lowest point there is 

 no irregularity in the action of the heart. On the contrary, 

 while in non-narcotized dogs immediately after the reinjec- 

 tion the heart beat becomes slower and sometimes irregular, 

 as the pressure falls the heart becomes and remains regular. 

 That the heart is not injured is furthermore shown by the 

 fact that with spasmodic expirations in which the abdominal 



