PR/tCTICAL DIRECTIONS. 431 



separate the bones at the sutures. The bones may then usually be 

 separated completely by hand. 



Entire skulls, and longitudinal sections, as represented in Fig. 

 43, p. 60, should be at hand. 



S/ut/y of Ihe Bones. — The bones should be studied in the order in 

 which they are described. No further special directions for their 

 study are necessary. 



Shidy of Ligameiils. — It will usually not be practicable for each 

 student to make the dissections and preparations necessary for study- 

 ing the ligaments. Rather should these be examined on demonstra- 

 tion preparations preserved in the laboratory. Such preparations 

 may most easily be made by using y>-(?j/z material, and dissecting 

 away muscles and other tissues, leaving only the ligaments connect- 

 ing the bones. The preparations are then preserved in one or two 

 per cent, formalin. It is difficult to prepare tlie ligaments satisfac- 

 torily on preserved material, because they do not stand out clearly 

 from other tissues in such material, so that they are not easily dis- 

 tinguishable. 



MUSCLES. 



Preparation and Preservation 0/ Ufaterial. — Formalin forms by far 

 the most satisfactory preservative for anatomical material. It is much 

 better in almost every respect than alcohol, and has the additional 

 advantage of being much cheaper. 



After injecting with formalin, the cat may be preserved either 

 immersed in a weaker solution of the same substance, or may be 

 kept for a long time simply wrapped in a cloth dampened with 

 formalin. The details of preparation differ according to which 

 method is to be used. 



In either case, the cat should be killed with chloroform, by 

 placing it in a tight jar or box with a cloth or bit of cotton saturated 

 with chloroform. It is not necessary to bleed the specimen. When 

 the cat is dead, remove it to a tray, place it on its back, and tie the 

 limbs loosely so that they will remain outspread. 



Expose the femoral artery in the thigh, as follows: Make a 

 median longitudinal incision through the skin of the abdomen, from 

 a point an inch or two caudad of the xiphoid process to the pubis. 

 Make an incision passing from near the middle of this obliquely 

 laterad onto the thigh, for about three inches. Reflect the two flaps 

 in the angles between these cuts, then with forceps and tracer isolate 

 the femoral artery just as it passes into the thigh (Fig. 127, a). 

 ]\Iakc with scissors an oblique incision in one side of the artery, one- 

 lialf to one inch from the point where it leaves the abdominal cavity. 

 Introduce a canula directed toward the body, and tie it in place. 



I. If the cat is to be preserved immersed in a solution of 

 formalin, it should now be injected with a five per cent, solution of 

 commercial formalin in ordinary water (commercial formalin 5 parts; 



