TREATMENT OF INJECTED PARTS. 169 



pressure is gradually increased by working the 

 syringe until a pressure of four or five inches is 

 attained. The blood in the vessels gets forced before 

 the injection into the right cavities of the heart, so 

 that these are soon much distended ; when this is 

 the case the right ventricle is slit open and the accu- 

 mulated blood allowed to flow out. The blood is 

 soon followed at first by a mixture of blood and the 

 colored gelatine, but afterwards 'by the latter only ; 

 after this has been escaping for a minute or two the 

 slit in the ventricle is closed by placing a clip on, 

 or tying a tape round the heart, and the injection 

 being thus obstructed in its outflow, accumulates in 

 the vascular system, and distends all the vessels to 

 their fullest extent. The success of the injection 

 may be estimated by the color of those parts which 

 are not concealed by the fur ; the paws, lips, nose, 

 and ears, for instance, and the tongue and interior of 

 the mouth. After waiting a few minutes longer, 

 until the vessels may be considered to be com- 

 pletely filled, a tape ligature is put round the base 

 of the heart, so as to include all the great blood- 

 vessels, and is slowly tightened. This will effectu- 

 ally prevent any escape of the fluid gelatine from 

 the vessels when the canula is removed from the 

 aorta, which may therefore now be done, the clip 

 having been first replaced on the India-rubber tube 

 which is connected with it, so as to prevent the in- 

 jection from spirting out. 



The animal is now put aside until it has become 

 quite cold and the gelatine is firmly set. The abdo- 

 men is then freely opened, and the skull-cap removed 

 (if the brain is wanted), and incisions having been 

 made through the skin of the limbs here and there, 

 the animal is placed overnight in weak spirit (equal 

 parts of water and spirit), and the next morning 

 those parts and organs which their color shows to 

 be well injected are carefully dissected out and 

 placed in rather stronger spirit. In another day or 

 two they may be transferred to the strongest spirit, 

 15 



