No. 462.) THE SKATE FOR ANATOMICAL STUDY. 371 
veins. Then, at a region about midway of the length of one 
lateral vein, and in a plane transverse to the long axis of the fish, 
make an incision into the muscle of the lateral wall of the 
abdominal cavity, carrying the incision across the lateral vein 
and somewhat dorsal to it (see the figure, page 377). The 
incision must be deep enough to admit of pressing apart the 
masses of muscle either side of the cut in such a way as to make 
easily accessible the two cut ends of the lateral vein. Immedi- 
ately, then, before the loss of the blood contained in the vein 
shall have made it difficult to see the vessel, thrust a probe or a 
coarse bristle forward into the cut end of its anterior division 
and another backward into its posterior division. A mass which 
“ sets” quickly may be injected without tying the cannula into 
the vein. For this purpose it is desirable to use a cannula of a 
size sufficient nearly to fill the lumen of the vein. Such a 
cannula, with the injection apparatus attached, may be inserted . 
successively into the two cut ends of the vein and held firmly in 
place with the fingers during the process of injecting. If it is 
desired to tie the cannula in place, the muscle may be cut away 
from around the cut end of the vein so as to leave about one 
centimeter in length of the vessel projecting, with more or less 
tissue attached to it. A ligature may then be passed around 
this. small projecting mass of tissue, including the vein, and, 
the cannula having been inserted, the ligature is tightened 
upon it. : 
The fluid which is injected into the anterior division of the 
lateral vein passes directly to the corresponding precaval 
(Cuvierian) sinus, whence it may pass into all the chief venous 
trunks of that side except as impeded by valves. It passes also, 
by way of the venous sinus, directly across to the opposite 
precaval sinus, whence it may enter the vessels of that side of 
the body. The cardinal and hepatic sinuses afford other, but 
less direct, routes for the passage of the fluid from one side to 
the other. In practice, this method usually results in the filling 
of both lateral veins and at least the proximal ends of the several 
brachial trunks. The mass fills also the postcardinal veins, in- 
cluding their posterior inosculation, the hepatic sinus and veins, 
the cardinal sinus, and the proximal ends of the inferior jugulars. 
