INJECTION OF BLOODVESSELS. 167 



or earthenware bottle capable of holding two or 

 three gallons, and tightly fitted with an India- 

 rubber cork, through which two glass tubes pass. 

 One of these is connected, as before mentioned, with 

 the injection bottle, and the other with a condensing 

 syringe (s), by means of which the air within the 

 bottle can be brought to any state of tension that 

 may be desired. "Finally, if the injection is to 

 occupy a considerable time, a water-bath or sand- 

 bath (?/?), heated by a ring-burner to about 40 C., 

 should be provided for receiving both the beaker 

 containing the injection-bottle and the animal, and 

 maintaining their temperature during the process. 

 Ordinarily, however, if the operation be quickly 

 and dexterously performed, the whole process will 

 not occupy more than a few minutes, and will be 

 over before the natural heat of the body has had 

 time to become dissipated. 



Everything then being in readiness, the animal, a 

 rabbit, guinea-pig, or rat, for example, is killed by 

 chloroform inhalation, being placed under a bell- 

 glass with a sponge wetted with chloroform. The 

 moment it has ceased to breathe, it is taken out and 

 held by an assistant, whilst the operator first quickly 

 reflects the skin from the front of the thorax and 

 then makes an opening in that cavity just over the 

 position of the heart. This is then seized near the 

 apex with blunt forceps, drawn out of the aperture, 

 and held here by an assistant, The aorta is then 

 found, the point of a pair of forceps passed under 

 it close to the heart, and a thread ligature drawn 

 round it. A snip is now made in the left ventricle, 

 and an arterial canula (Fig. 29, e') passed through 

 this into the aorta, in which it is tied by the liga- 

 ture. Then by means of a pipette a little warm 

 water or salt solution is passed into the canula so 

 as completely to fill it to the exclusion of air. 



^The next thing to do is to connect the canula 

 with the India-rubber tube which brings the injec- 

 tion from the bottle. But this tube must first be 



