14 KLEMEMS OF MAAlAl ALLAN ANATOMY 



Preparation of a Mammal for Dissection of the Muscles, 

 Peripheral Nerves and Viscera. — The simplest method is to 

 anesthetize the animal as before described and then remove the 

 skin, taking great care to avoid cutting away the superficial 

 muscles. The cannula should be pushed through into the tra- 

 chea and ICO c.c. of 15% formalin injected to fill the lungs. 

 An equal amount of formalin should be injected into the 

 stomach through a glass tube pushed down the esophagus. The 

 same quantity of formalin should be injected at two or three dif- 

 ferent places into the intestines by making a median incision 

 into the abdominal wall and pulling out a loop of the intestine 

 into which the cannula may be thrust. The specimen is then 

 to be immersed in a jar of 5% formalin. A better method is to 

 inject into the carotid artery 200 c.c. of glycerinated formalin 

 (water 140 c.c, glycerin 30 c.c, formalin 30 c.c), and half that 

 amount into the intestine and trachea. The specimen may 

 then be preserved in 5% formalin. 



Preparation of the Central Nervous System. — The animal 

 may be killed either with chloroform or ether. About 200 c.c 

 of formal-bichromate (170 c.c. of 5% potassium bichromate 

 and 30 c.c of formalin) are then injected slowly craniad into 

 the carotid artery (Figs. 2, 3, and 4). After skinning, the eyes 

 should be cut out and the flesh removed from the head and 

 dorsal side of the vertebral column. On a line connecting the 

 caudal borders of the orbits, cut through the skull to the brain 

 with the bone cutters and remove piece by piece the roof of the 

 skull. Next cut away the lateral walls down to the base of the 

 brain. Care must be exercised in laying bare the cerebellum, 

 and cutting loose the tentorium cerebelli, the plate of bone 

 separating the cerebrum from the cerebellum. The spinal 

 cord is next laid bare dorsally, beginning with the atlas, by 

 cutting through the pedicles of the neural arches on either side. 

 With a sharp knife or a pair of scissors the spinal nerves may 

 then be cut and the cord lifted from behind forward out of its 

 bed, until the brain is reached. The latter must be carefully 



