a2 ALLEN 
V.); or, if this vessel is absent, from one of the intestinal veins. 
If desirable to fill the caudal, neural, and hemal veins, a sepa- 
rate injection of the caudal vein (fig. 1, Cau.V.) is usually re- 
quired. The entire arterial system can be filled from one of 
the gastric arteries (fig. 1, L.Gas.A.), but an easier and more 
satisfactory way, especially if the fish has no air-bladder, is to 
make 2 injections of the dorsal aorta at a point marked X (fig. 
1), shortly before it penetrates the kidney and posterior to the 
origin of the cceliaco-mesenteric and subclavian arteries. A 
cannula the proper size, having a rubber tube attached, was 
slipped cephalad into the vessel and ligatured. If the aorta is 
small, the rubber tube and cannula can be used as a blow pipe 
to help open itup. The syringe is then filled with the Berlin 
blue injecting mass; as much air as possible is sucked out of 
the tube and vessels before connecting the tube with the syringe ; 
with a slow, steady movement, the mass is forced cephalad into 
the aorta, from whence it passes into the carotids, efferent bran- 
chial vessels, cceliaco-mesenteric and subclavian arteries, and 
finally in like manner, from the same place, the aorta is in- 
jected caudad, which fills the vessels of the kidney, reproduc- 
tive organs, body wall, and tail. 
In tracing out the small peripheral vessels of the head, fins, 
and viscera, I have found it very satisfactory to inject alone 
the head, fins and viscera of a 15 to a 40 pound fish. The 
head is severed dorsally several inches behind the skull, includ- 
ing the pectoral and ventral fins, being careful not to cut or 
injure any of the visceral organs. A ventral slit is then made 
through the entire ventral wall to the vent; the intestine is cut 
at the rectum, and the entire viscera pulled out with the head. 
In this manner the fish is cleaned, spoiling very little if any of 
the flesh, after which the 2 cut ends of the cardznails (Pl. I, fig. 
1, L. & R.Car.V.), and the posterior end of the ventral artery 
(Pl. Il, fig. 12, Ven.A.), if cut, were ligatured. Two injec- 
tions, as described in the previous paragraph, were made; one 
from the hepatic vern, and the other cephalad from the cut end 
of the dorsal aorta. 
In most cases it is best to make the dissections while the 
material is fresh. Asa preserving fluid I find nothing better 
than formalin; it does not extract colors as does alcohol, and 
