372 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



specimens in order that the brain may harden. In the case of mammals additional measures 

 are necessary in order to insure preservation. Mammals should be embalmed. This is done 

 by injecting an embalming fluid into the blood vessels before the injection fluid is sent in. The 

 embalming fluid may consist of 5 per cent formalin or better 5 per cent formalin plus one-sixth 

 its volume of glycerin. A still better but more expensive embalming fluid is one used for human 

 bodies, with the following formula : 



Parts by Volume 



Formalin . . 1.5 



Carbolic acid (melted crystals) 2.5 



Glycerin ... 10.0 



Water 86.0 



The embalming fluid is injected preferably into the femoral artery through a cannula in the same 

 way as already described for the injection fluid. Bensley recommends that the injection of 

 the embalming fluid should be done, not with a syringe, but by attaching the cannula to a 

 receptacle containing the embalming fluid elevated about three feet and allowing the fluid to 

 run into the vessel under this pressure for about two hours. The animal should be arranged 

 in a position suitable for dissection, with the limbs spread well apart and the head tilted back- 

 ward. After the embalming the injection fluid is run into the same cannula by attaching the 

 syringe to it ; Bensley recommends that twenty-four hours elapse between the embalming and 

 the injection with the colored fluid. 



If the animal has been thoroughly embalmed, it will keep without being immersed in a 

 preserving fluid. It should be prevented from becoming dry by being placed in air-tight 

 receptacles or wrapped in cloths saturated with the formalin-glycerin solution. It is best to 

 sponge the hair with a mixture of alcohol and water containing 2 per cent formalin. The 

 animals may, however, if preferred, be immersed in 1 per cent formalin solution. During the 

 dissection the animals should be kept wrapped in cloths moistened with formalin glycerin. 



Further details on these matters will be found in: Bensley, Practical Anatomy of the Rabbit 

 (University of Toronto Press); Reighard and Jennings, Anatomy of the Cat (Henry Holt and 

 Company); and Davison, Mammalian Anatomy (P. Blakiston's Son and Company). 



5. Dealers. — Preserved and injected material necessary in the course can be obtained from : 



The General Biological Supply House, 1177 East 55th Street, Chicago. 



Supply Department, Marine Biological Laboratory, Woods Hole, Massachusetts. 



The Angler's Company, 913 West Randolph Street, Chicago. 



Live Necturus, turtles, pigeons, etc., are also obtainable from the first and third dealers 

 named above. The General Biological Supply House can also furnish prepared skeletons of 

 any forms. For the names of other dealers consult Science, Transactions of the American 

 Microscopical Society, and similar journals. 



