The Preservation of Material. 285 



At the time of beginning the embalming process the operator 

 should have before him the reservoir, suspended at a height of 

 about three feet, and a column of fluid, free from air-bubbles or 

 foreign material to the tip of the cannula. This condition must 

 be maintained throughout the operation. If at any time the 

 pressure falls in the apparatus sufficiently, to admit air, or allow 

 coagulated blood to run back through the cannula, there is almost 

 certain to be trouble, not only with the specimen under treatment, 

 but also others which come after. The column of fluid is held back 

 until the proper time by a clamp placed on the rubber tubing. 



The animal is killed by administering ether or illuminating gas. 

 It is placed on its back oa the table, with the head away from the 

 operator. The skin is first divided by a small incision on the inner 

 side of the right thigh.* By inserting the fingers well down into 

 the incision, the skin may be torn backward and toward the ventral 

 middle line, and at the same time the superficial epigastric vessels 

 will be carried with the subcutaneous tissue well out of the oper- 

 ator's way. Small portions of the inner surface of the thigh and 

 of the abdominal wall will be exposed. The white cord repre- 

 senting the inguinal ligament lies in the bottom of the inguinal 

 furrow. Appearing from beneath the ligament in this position, 

 and passing to the surface of the thigh are the femoral nerve, 

 artery, and vein, covered by an exceedingly thin layer of muscle 

 belonging to the sartorius. The three structures may be separated 

 from one another, and the muscle pulled away at the same time, 

 by working lengthwise along the structures with the fine, forceps. 

 The artery must be 'thoroughly cleared for about 3 cm. from the 

 inguinal ligament. Care must be exercised in this operation to 

 avoid breaking its branches or the tributaries of the vein. The 

 artery lies in front of the vein and is distinguishable by its smaller 

 size, flattened or collapsed condition, and by its white coloration. 

 The vein will be found greatly distended with blood. The nerve 

 lies in front and partly on the lateral side of the artery. 



When the femoral artery has been fully exposed, a ligature of 

 coarse thread, previously moistened, may be passed around its base, 



*The embalming may be done from the common carotid artery of the neck, a 

 vessel much larger than the femoral artery and therefore easier of manipulation. 

 This is not recommended, however, because of the damage done to various 

 important structures of the cervical region. 



