xi PRACTICAL DIRECTIONS 543 



of an adult, should be obtained for examination : the former is the more 

 important of the two for making out the individual bones, which should 

 all be separated from one another by prolonged maceration in water, or 

 by boiling for a short time. In the adult skeleton the bones are best 

 kept in their natural connection. An additional skull should be 

 prepared, and a longitudinal vertical section made of it with a fine saw ; 

 but as it is difficult to do this very accurately and perfectly in the 

 rabbit, owing to the delicacy of some of the bones, the skull of a young 

 dog or cat may be used for the purpose. 



Work through the account of the skeleton given on pp. 487-505, as 

 well as of the teeth on pp. 509-5 1 1 , comparing the form, number and 

 arrangement of the teeth in the herbivorous rabbit and the carnivorous 

 dog or cat, noting the presence of canines in the two last mentioned. 

 Sketch typical parts of the skeleton. 



C. Superficial dissection, and injection of the arteries. 



Fix the animal on its back on the dissecting-board by inserting large 

 pins through the limbs. If you wish to inject the arteries, cut through 

 the skin on the inner side of one of the thighs, reflect it, and with the 

 seeker expose the femoral artery (p. 524) ; or if your specimen is a small 

 one, expose one of the carotid arteries (p. 523) instead, by carefully 

 cutting through the skin along the middle ventral line of the neck. 

 Pass a piece of thread round the artery thus laid bare, and make a small 

 slit in it with the fine scissors distally to the thread. Insert and tie in 

 a cannula, and first inject a little strong formaline (i part formaline 

 and 2 parts water), following this with the coloured starch injection- 

 mass (p. 99), which will force the formaline into the capillaries and help 

 to preserve the specimen : this method is of special advantage for 

 the subsequent examination of the enteric canal, especially if it is not 

 possible to get to the end of VI, p. 547, on the first day ; the veins 

 need not be specially injected, as they will be naturally injected with 

 blood. 



Make a median longitudinal incision through the skin in the sternal 

 region, and continue the cut backwards to the pelvic symphysis and 

 forwards to the mandibular symphysis ; then dissect away the skin 

 from the underlying muscles over the whole ventral surface, being 

 careful not to injure any of the larger blood-vessels (e.g., the jugular 

 veins in the neck). Note : 



i. The thin cutaneous muscle, part of which you have very likely 



