I NT ROD UCTION. 



Iv 



with this is a cylinder of tin (A), which is filled with water, and is raised or lowered by 

 means of a cord which passes over a pulley (p) fixed to the ceiling of the room. 



INJECTION OF THE BLOOD-VESSELS OF AN ENTIRE ANIMAL. 



Having determined which injection-mass is to be used, prepare the cannulae. The animal 

 a rabbit or guinea-pig whose blood-vessels are to be injected, is killed by chloroform. As 

 soon as it ceases to breathe, the thorax is opened by making an incision along the middle of 

 the sternum, so as to expose the heart. Pull the heart forward, and open the pericardium. 

 Snip through the wall of the right auricle, and 

 allow as much blood to flow out as possible ; the 

 animal may even be suspended by the hind limbs 

 to expel as much blood as possible. Expose the 

 aorta, and tie into it a glass cannula (fig. 23, c} 

 as directed at p. Hi. The cannula is now filled 

 with salt solution, and is connected either with a 

 syringe or one of the constant-pressure arrange- 

 ments described above. Take care that there 

 is no air either in the cannula or in the india- 

 rubber tube coming from the injection-bottle. At 

 first a pressure of two inches of mercury is suffi- 

 cient, but gradually the pressure may be raised to 

 four inches. As the injection is forced into the 

 aorta, and gradually fills the blood-vessels, blood 



and then blood and injection-mass flow out of 



the right auricle. Continue the injection until the 



injection alone flows from the hole in the right 



auricle. It is then closed by a broad ligature, and 



the injection continued until the vascular system is 



filled with the injection, which may be judged of 



by the colour of transparent parts, as the ears, lips, 



&c. After the injection is complete, ligature the 



vessels at the base of the heart, or a glass stopper 



may be put into the caoutchouc tube attached to 



the glass cannula. The after-treatment of the in- 

 jected animal is described at p. Hi. 



If an animal be allowed to cool after death, it 



must be thoroughly warmed before using a gelatine 



mass. This is done by placing it for an hour in 



warm water not above 40 C. 



Fig. 26. INJECTION APPARATUS WITH WATER 

 PRESSURE. 



A, Vessel filled with water; B, Bottle for compressed 

 air ; c, Bottle for injection mass ; M, Manometer. 



INJECTION OF THE LYMPHATICS. 



Puncture Method. This is very easily done by the ' einstich ' or ' puncture ' method of 

 Ludwig. A small subcutaneous (Pravaz) syringe (fig. 27, p. 22) is filled with a two per cent. 



