xi PRACTICAL DIRECTIONS 543 



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. 509-511, 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 ; sections 

 of the teeth (see p. 510) should be examined. Sketch 

 typical parts of the skeleton. 



C. Superficial dissection, and injection of the arteries. 



[For the blood-corpuscles, examine a drop of blood obtained 

 from a freshly-killed rabbit, or by pricking the tip of your 

 finger (compare p. 121). Note the circular and slightly 

 biconcave form of the red corpuscles, their relatively small 

 size (about ^o 1 ^ in. or -008 mm. in diameter), and the 

 absence of a nucleus.] 



i . Fix the animal on its back on the dissecting-board by 

 inserting large pins or nails 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 speci- 

 men 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 distal ty to the thread. Insert and 

 tie in a cannula, directed towards the body, 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 sym- 



