274 



Experimentation upon Animals 



pulled out, -leaving a clean surface an inch square. The 

 skin is then washed with a disinfecting solution, an incision 

 one and a half inches long made through the skin and 

 superficial fascia in the middle line of the neck, the tissues 

 carefully separated, the deep fascia cautiously opened, the 

 tissues separated with the point of the forceps and a 

 grooved director, the sheath of the ves- 

 sels opened, and the artery completely 

 separated from its surrounding tissues 

 for a distance of at least an inch. A 

 ligature is now tightly tied about the 

 artery at the distal end of exposure, and 

 a ligature placed in position and loosely 

 looped ready to tie about the proximal 

 end. A tube with a sharp lateral tubu- 

 lature, as is shown in the illustration 

 (Fig. 78), is now made ready by break- 

 ing off the closed tip, the moistened 

 forefinger of the operator is placed be- 

 neath the artery, and the sharp tube 

 inserted (point toward the heart) into 

 the artery, through whose walls it cuts 

 its way easily. The moment the vessel 

 is entered the blood-pressure drives the 

 blood into the tube so that 20 c.c. may 

 be collected in about as many seconds. 

 An assistant now ties the artery at its 

 proximal end, the tube is withdrawn, 



.- 7f- Tube for holding it so that the blood does not 

 taking blood from the , . 



carotid artery of a escape, and the end sealed in a name, 

 rabbit or guinea-pig. The ends of the ligatures are now cut 

 short and the external wound stitched. 

 The wound usually heals at once, and if subsequent study of 

 the blood is required, the other carotid and the femorals 

 can be similarly employed for obtaining it. 



Small quantities of blood (drops) can be secured from 

 mice and rats by cutting off the tip of the tail, but to 

 secure a large quantity is difficult. One method that has 

 been recommended is to tie the animal to a tray or board, 

 on its back, anesthetize it, and, just before it dies, quickly 

 open the thoracic cavity, and cut through the heart with 

 scissors. The animal at once dies, the blood pouring out 



