ON INJECTING BLOOD VESSELS, ETC. 75 



capacity of a litre or more, a mercurial manometer, 

 a Higginson's syringe, a spirit lamp, or a Bunsen's 

 gas burner, some glass and brass cannulae, and 

 some india-rubber tubing, two clamps (one for 

 the pressure tube, the other for the delivery tube), 

 will also be required. 



To make an injection of an animal with a gelatine 

 mass, proceed as follows : 



Fill the water-bath with water of a temperature 

 of from 40 to 45 C. Keep it at this temperature 

 by placing a spirit lamp or a Bunsen gas burner 

 under the bath. Melt the gelatine mass and pour 

 it, through flannel, into the two-stoppered Wolffs 

 bottle. Place this bottle in the place provided for 

 it in the bath the bottle should be weighted to 

 prevent its floating as the fluid is withdrawn from 

 it. Arrange the manometer, pressure bottle, syringe 

 and basin (or water-bottle), as shown in illustration. 

 Now chloroform the animal to be injected, and pro- 

 ceed as already described ; affix the cannula, tie it 

 securely into the aorta, and after washing away all 

 blood from the thorax, &c., place the animal in the 

 water-bath. The animal must be submerged in the 

 water, but not too deeply. Clamp the delivery tube 

 of the bottle containing the injection fluid and, with 

 the syringe, pump into the pressure-bottle from 

 the basin or water-bottle sufficient water to raise 

 the mercury in the manometer one inch; remove 

 the clamp from the delivery tube, allow the air to 

 escape from it, and immediately connect it with the 

 canuula. The tube must remain submerged whilst 

 the connection is being made. Now keep up an 

 equable pressure by means of the syringe, and when 

 the mercury in the manometer shall have risen to 



