BLOOD-VASCULAR SYSTEM OF THE LORICATI 3 1 



mass shortl}'' before using. This mass has a beautiful yellow 

 color, having a ver}^ fine precipitate, which easily passes 

 through the fine capillary net-works of the gills, pseudobranchice, 

 and retia mirabilia of the eye. 



A carviinc sohition 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. Affaraius. 

 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 i^ 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 hefatic vein (PI. I, fig. i, 

 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 sinus 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 (PI. I, fig. i ; P.Mes.- 



