230 ANIMAL PHYSIOLOGY. 
Fic. 207.—Apparatus used in makine a blood-pressure experiment (after Foster). pb, pressure- 
bottle, elevated so as to raise the pressure several inches of mercury, as seen in the ma- 
nometer (m) below. It contains a saturated solution of sodium carbonate ; r.t. rubber tube 
connecting the pb with the leaden tube ; l.t, tube made of lead, so as to be pliable, yet have 
rigid walls ; s.c. a stop-cock, the top of which is removable, to allow escape of bubbles of 
air ; p, the pen, writing on the roll of paper, 7. The former floats on the mercury ; m, the 
manometer, the shaded portion of the bent tube denoting the mercury, the rest is filled 
with a fluid unfavorable to the coagulation of the blood, and derived from the pressure- 
