OBTAINING LARGE AMOUNTS OF ANIMAL BLOOD 47 



The bottom of a large sterile test-tube is heated and drawn out to a 

 fine point, as shown in the illustration (Fig. 22), and the tip is broken 

 off. The operator now places his moistened forefinger under the ar- 

 tery, elevating it up and rendering it taut ; the tip of the tube is then 

 passed through the wall into the interior of the vessel toward the heart. 

 The moment the vessel is entered the blood-pressure drives the blood 

 into the tube, so that 20 c.c. are soon secured. An assistant now ties 

 the ligature below .the site of puncture; the tube is withdrawn, and the 

 tip sealed in a flame. The ends of the ligatures are cut short and the 

 wound is stitched. Healing usually occurs at once, and if subsequent 

 study of the blood is required, the other carotid and the femorals can 

 be used similarly for securing it. 



Fourth Method. The animal is fastened to the operating board, and 

 the hair over the neck and thorax moistened with alcohol or lysol solu- 

 tion. The right thorax is then incised and held open by an assistant. 

 The right lung is seized with sterile forceps and quickly severed at the 

 base with sterile scalpel or scissors. The heart is then punctured, and 

 the blood is quickly removed from the thoracic cavity with a sterile 25 

 c.c. pipet with a large opening. Unless the lung is removed, it tends to 

 float and block the end of the pipet. Everything must be in readiness, 

 as otherwise blood will be lost, flooding the thoracic cavity. 



Guinea-pig. Pig serum is usually secured to furnish complement in 

 hemolytic tests, and should be used within twenty-four or forty-eight 

 hours after bleeding. Precautions to insure sterility are not, therefore, 

 usually necessary. 



1. The animal is anesthetized with ether and the large vessels of the 

 neck on one side are exposed by a longitudinal incision. These are 

 severed, and the blood is collected in a Petri dish or in a centrifuge tube 

 by means of a funnel (Fig. 23). 



2. By means of a sharp-pointed scissors the vessels on one or both 

 sides of the neck may be incised transversely at one cut, inserting the 

 blade deeply and close to, but avoiding, the trachea and esophagus. 



Rats. 1. Small quantities of blood may be obtained by snipping 

 off the tip of the tail of the animal and milking blood into an appropriate 

 sterilized tube containing glass beads, or 2 per cent, sodium citrate 

 solution. In this manner one or more cubic centimeters of blood are 

 easily obtained, and at once defibrinated and injected into the perito- 

 neal cavities of other animals, as in inoculating trypanosomes, etc. 



2. Large quantities of blood are obtained by severing the large vessels 

 of the neck, under anesthesia. 



