APPENDIX B 371 



piece of rubber tubing. The whole system should be filled with the injection fluid in advance, 

 in order to avoid forcing air into the blood vessels. After everything is ready inject the solution 

 into the blood vessel by a steady but not too forceful pressure on the syringe or bulb. The suc- 

 cess of the injection should be determined by examining the small vessels of the skin or in the 

 intestinal walls. When these are deeply colored the injection is complete and the cannula is 

 then withdrawn, the cord being immediately tightened around the blood vessel and tied with a 

 double knot to prevent leakage. In case only the arterial system is injected, as is usually the 

 case, the blood should not be let out of the animal; the injection will force the blood around 

 into the veins and distend them. If the systemic veins are to be injected, the blood should be 

 drained from the animal by opening the vein, at the place where it is to be injected. 

 The following formula for the injection fluid is given by Davison: 



100 c.c. of water 

 20 c.c. of glycerin 

 20 c.c. of concentrated formalin 

 85 gms. of corn starch 

 sufficient coloring matter to give a deep color. 



Stir thoroughly and strain through fine cheesecloth. All lumps must be removed. As 

 the starch settles to the bottom on standing, the mixture must be stirred before using. Color- 

 ing matter used in the injection mass is: for red color, vermilion (mercuric sulphide); for 

 yellow color, chrome yellow (lead chromate); for blue color, Prussian blue. The injection 

 fluid will keep indefinitely. 



Injection is usually made into the following vessels: in elasmobranchs, the arteries are 

 injected by way of the caudal artery, exposed by cutting across the tail; the hepatic portal 

 system is injected by way of the hepatic portal vein near the liver backward or in both direc- 

 tions or into the posterior mesenteric vein forward. Injection of the systemic veins is more 

 difficult and is usually not done; a method is given by Rand in the American Naturalist, Vol. 

 XXXIX (1905). In Nectv-rus the arteries are most easily injected by way of the bulbus 

 arteriosus. The hepatic portal system should be injected in both directions into the hepatic 

 portal vein just before it enters the liver. The postcaval can be injected, if desired, through 

 the large hepatic vein seen on the ventral surface of the liver just behind the transverse septum. 

 The arterial system of the turtle is injected either backward by way of one of the carotids or 

 into the left aorta away from the heart. It is practically impossible to work out the renal 

 portal and hepatic portal systems on preserved turtles unless they are injected. Injection is 

 very easily made of both of these systems by way of the abdominal vein. The plastron is, of 

 course, to be removed by sawing across the bridges. Insert the cannula into one of the abdomi- 

 nal veins about halfway between the heart and pelvis and inject forward. Injection of the 

 arterial system of the pigeon can be done by way of the pectoral artery toward the heart. 

 According to Parker the systemic veins and the hepatic portal system may be injected by way of 

 the coccygeo-mesenteric vein, in both directions. The arterial system of mammals is injected 

 either by way of the carotid or the femoral artery, the cannula being directed toward the heart. 

 The veins are usually not injected, but it is stated that they may be injected by way of the 

 external jugular toward the heart. The hepatic portal system may be injected by way of the 

 hepatic portal vein near its entrance into the liver. In injecting arteries and veins in the same 

 specimen, differently colored injection fluids should, of course, be used. 



4. Preservation of specimens. Specimens are usually preserved in 5 per cent formalin 

 (5 c.c. of commercial formalin plus 95 c.c. of water). A slit should be made in the body cavity 

 or the formalin should be injected into the body cavity through a small opening to insure pres- 

 ervation of the viscera. A portion of the roof of the skull should be removed in the smaller 



