The next step is to inject the arterial system. For this purpose a different point for injecting the system is selected from the one pointed out in the former process. By removing the small intestines out, and on the right side of the body the descending branch of the aorta is exposed to view. In its course downwards, the aorta lies on the vertebral column to the left of the middle line, and terminates on the fourth lumbar vertebra, by dividing into the two common iliac arteries. The descending branch of the aorta is then punctured so as to admit the nozzle of the injector; this is introduced into the opening in an upward direction, and the walls of the artery are then tied firmly, but not so as to cut through, around the nozzle. After the artery has been thus prepared, and before injecting, the vena cava must be perforated at a point corresponding with the incision practiced in the descending portion of the aorta where the nozzle of the injector is inserted. The inferior vena cava ascends _along the front of the vertebral column_, and to the right of the abdominal aorta. The object of severing this vein is to give the blood in the upper portions of the body a means of escape, as the fluid is forced through and up the arteries of that part and returning through the veins forces the blood through the opening. After the upper portion of the body has been injected with about half a gallon of the embalming liquid, the nozzle of the injector must be reversed and the lower parts injected in a similar manner with about the same amount of liquid; the injection must then be stopped for the space of about three hours, and all the blood which may have escaped from the opening made in the vena cava into the cavity of the intestines must be sponged out as it fills up the space left. The mode of injecting is also of extreme importance. The injection should be done slowly and steadily, as a strong, sudden forcing up of the liquid into the arteries might occasion a rupture of their walls should some point be weakened from some cause arising from previous sickness, or from lesions as described in a previous chapter. The injection may then be renewed and more liquid be injected, until a sufficient quantity has been used. As there are no rules laid down for the amount of liquid to be injected, it is left altogether to the discrimination and good judgment of the operator. The bodies of children and old persons will require less liquid than adults up to the age of forty. The bodies of persons killed by accident or some sudden cause, will require a larger amount of liquid than those of persons who are emaciated by long illness, as, for instance, consumption. After the arterial and venous system have been thus completely injected, the intestines must be replaced in the abdominal cavity. The brains must next be removed, and this operation is one which requires extreme caution, as will be seen by the following explanation of the process.