BLOOD-VASCULAR SYSTEM OF THE LORICATI Bolt 
mass shortly before using. This mass has a beautiful yellow 
color, having a very fine precipitate, which easily passes 
through the fine capillary net-works of the gills, pseudobranchie, 
and retia mirabilia of the eye. 
A carmine solution is prepared by mixing some carmine with 
water; enough ammonia is added to dissolve the carmine, giv- 
ing it a dark brown color. The mass is then neutralized with 
acetic acid, and when neutral it will change to a bright red 
color. If desired to keep for some time, add chloral hydrate. 
Like the Berlin blue solution it can be injected as it is; or it 
can be mixed with a gelatin mass in the same proportions. 
2. Apparatus. 
The apparatus consisted of a number of glass cannulas of 
various sizes, fastened to short, but stout rubber tubes; a 4-oz. 
rubber syringe, and a % oz. rubber syringe. The latter, 
when connected with a rubber tube and a small glass cannula 
makes the best kind of a hypodermic syringe. 
3. Mode of Procedure. 
When the arteries and veins are to be injected with different 
colors, it is best to inject the venous system first. This can 
generally be accomplished from the hepatic vezn (PI. I, fig. 1, 
Hep.V.). <A ligature is placed under the vein and tied loosely ; 
a slit is made in the anterior portion of the liver, and a large 
cannula attached to a rubber tube is forced cephalad in the vein 
into the szmus venosus. 'The blood was sucked into the tube, 
and then blown out; this process was repeated, until the sinus 
and other vessels were cleared of blood, and the cannula was 
again inserted into the vein and ligatured. Then the syringe 
was filled with the yellow injecting mass, but before connecting 
with the rubber tube, all the air possible should be sucked out 
of the tube, sinus, and other vessels. With a slow steady stroke 
the mass is forced into the sinus venosus; from thence through 
the heart to the gills; through the precava to the jugular and 
cardinal veins, and usually it would pass through the other 
hepatic vein and the venous capillaries of the liver, thus filling 
the portal system. If this fails, the portals can easily be in- 
jected from the posterior mesenteric vein (Pl. I, fig. 1; P.Mes.- 
