6 
posing the external jugular veins (Fig. 3). 
ELEMENTS OF MAMMALIAN ANATOMY. 
With the 
curved forceps thrust beneath the vein a cord may be pulled 
4 
3. DIAGRAMMATIC VIEW OF 
OPERATION FOR INJECTION. 
d, Broken line showing course of 
the carotid artery beneath; b, 
string loosely tied; c, transverse 
vein uniting external jugulars; 
a, points of curved forceps con- 
taining string. 
Fic. 
through and tied in a loose 
knot. One-half inch from 
the latter a second cord 
should be tied around the 
vein loosely. An_ oblique 
cut (Fig. 4) with the point 
of the scissors directed cau- 
dad is then made in the veins 
between the cords. The in- 
cision should extend about 
half-way through the vessel. 
Absorbing the blood with 
absorbent cotton as it runs 
from the vessel will prevent 
clogging. Iftoomuch ether 
has not been used, the blood 
will continue running fifteen 
minutes. When it has nearly 
ceased flowing, the carotid 
artery must be found by 
making a slit in the muscle alongside of the trachea just 
mediad of the jugular, as indicated by the line d (Fig. 3). 
Having cut through the muscle, 
two white cords are seen along 
either side of the trachea. 
The medial one may be red, as 
it is the carotid artery. The 
lateral one, lying in the same 
sheath with the preceding, is 
the vagus tenth 
nerve. Separate the 
cranial 
artery 
or 
Fic. 
INCISION 
ARTERY FOR INJECTION. 
MetuHop oF MAKING 
IN THE CAarRoTID 
4. 
from the nerve and tie two cords loosely around the ves- 
