THE RABBIT 199 



(2) Cut the skin around the neck just back of the 

 head, and pull it over the head. Is the skin the same thick- 

 ness on the dorsal and ventral sides? Why? Notice the 

 muscles running to the ears. Note how they meet on the 

 neck. To what are they attached? What motions have 

 the ears? Of what value are these movements? Notice 

 the ring of cartilage around each ear. Describe it. Re- 

 move the skin from the head. Do you find indications of 

 bilateral symmetry? What are they? Cut down through 

 the muscles and see if you find other indications of bilateral 

 symmetry. 



(3) Remove the brain in the following manner; Insert 

 the bone forceps or scissors into the skull just over the base 

 of the ear and cut forward to a point between the eyes. 

 Cut from the base of the other ear in like manner to the 

 same point. Then cut across at the base of the skull and 

 remove the bone. If the cutting has been carefully done 

 the brain will be uninjured. Remove the remaining bone 

 at the base of the skull, exposing the medulla oblongata. 

 Cut the spinal cord just behind the medulla, lift brain 

 from back forward, cut the nerves as far from the brain 

 as you can, and finally remove the brain and put it in sixty 

 per cent, alcohol or in Mueller's fluid. Put the brain aside 

 for future study. Observe the inside of the brain cavity. 

 Do you find joints? What kind? Compare with brain 

 cavity of frog and bird. Explain the differences. 



(4) At the base of the skull note the articulation of 

 the first cervical vertebra, the atlas, with the two projec- 

 tions, the occipital condyles, of the skull. Twist the head 

 to find out the freedom of movement. Study the articula- 

 tion of the second cervical vertebra, the axis, with the first. 



