THE SNAPPING TURTLE. 229 
The effect of muscular movement upon the pressure of the blood in the arteries was 
well marked and interesting. During violent movement the force of the heart remained 
unaltered, but the whole column of mercury rose, a result which attained to a maximum 
when the movements were coincident with the long inspiration and the short expiration 
which terminate each single series of respiratory movements. On such occasions the 
mercury sometimes rose as high as 70 m.m. and the action of the heart was irregular 
and unequal in force. Immediately after the movements were over, the mercurial column 
fell to a much lower point than usual, and then gradually ascended to the normal stan- 
dard, as illustrated by the following record. 
E:XPERIMENT.—Snapper. Weight 243 lbs. Temp. of air 78° F. Tube in left carotid. 
Not all the respiratory acts were here noted: 
TIME. MINIMUM. MAXIMUM. 
4.45 33 M.M. 49 M.M. 
4.47 34 51 
4.48 33 49 
20 50 During violent struggles the heart acting irregu- 
larly. 
4.55 31 46 Pulse 27. 
5.06 33 51 Free movement. 
6.11 31 46 
5.13 15 + 70 Prolonged movements and active respirations, 
during which this rise took place. 
31 46 
5.21 34 47 Movement. 
5.27 27 33 
5.28 3 40 Movement very violent. 
5.29 10 18 
5.34 32 44 
5.343 33 45 Pulse 28. 
VENOUS BLOOD-PRESSURES. 
The arrangement of the veins of the neck in the Snapper favor peculiarly an exami- 
nation of the blood-pressure$, since they are so large and numerous that an interruption 
of the current in one of them does not at all interfere with the general flow of blood 
towards the heart. 
Both carotids are accompanied by one large internal jugular vein, and sometimes by 
two. The external jugular is also very large, and the cesophagus is surrounded by a 
plexus of anastomosing veins of large dimensions. At the back of the neck there are 
also one or two dorsal veins of considerable size. 
ExprrIMENT.—Turtle. Weight 20 lbs. The tube was placed in the distal end of the 
internal jugular vein, when the mercury rose to 6 m.m. and was seen to pulsate feebly, the 
column rising about 4 m.m. at each heart-pulse. Violent motion raised the column to 11 
