450 poisons : their effects and detection [§ 556. 
Dr Johnson has described, as the stop-cock action of the small arteries 
comes into play, the small arteries contract and attempt, as it were, to 
limit the supply of poisoned blood. Ackermann, 1 indeed, witnessed this 
0 5 !0 15 20 25 30 35 40 45 50 55 60 minutes. 
Curve showing changes in the pulse and arterial tension produced by 
intravenous injection of infusion of digitalis in a dog. 
phenomenon in a rabbit’s mesentery, distinctly seeing the arteries 
contract, and the blood pressure rise after section of the spinal cord. 
This observation, therefore, of Ackermann’s (together with experiments 
Deutsch. Arch. f. klin. Med., xix. 125 . 
