82 



Animal Micrology 



Although not as desirable in the main as the method of continu- 

 ous air pressure, many good injections may be made by means of 

 the syringe. The apparatus (Fig. 35) consists of a syringe fitted 

 with a stop-cock in the nozzle, and a separate tube, known as the 

 cannula, which fits on to the end of the nozzle. 

 The syringes are made in different sizes and 

 each is provided with an assortment of cannulae 

 to fit vessels of different caliber. 



1. Provide yourself with several strong 

 threads about four inches in length for ligat- 

 iiig blood vessels. Have the red injection 

 mass melted and heated to about 50 C. Also 

 have ready some hot water to warm the syringe. 



2. Kill a cat or a rabbit bv means of chloro- 



j 



form. In death from chloroform the blood ves- 

 sels are left dilated. Work rapidly so that the 

 entire animal may be injected while yet warm. 

 Stretch it out in a dissecting pan or tie it out 

 onto a board. 



3. Slit the skin along the ventral surface of 



FIG. 35. Injecting 

 Syringe. 



the body to the middle of the neck and reflect 



it to the right and left sides. Pin it back out of the way. 



4. Snip a small hole through the body wall just posterior to 

 the ensiform cartilage. Insert the index finger of the left hand 

 to guide the scissors and prevent injury to the underlying organs, 

 and cut the costosternal cartilages of the right side up to the first 

 rib. In like manner cut the cartilages of the left side up to the 

 first rib. 



5. Ligate the sternum tightly as close to the first ribs as 

 possible to prevent leakage from cut blood vessels. 



6. Cut off the apex of the heart and expose the ventricles. 

 The left ventricle is seen as a round opening, the right as a slit. 



7. With a sponge wrung out of warm water, rapidly absorb 

 the blood from the thorax. 



8. Choose the largest cannula that the aorta will admit and 

 thrust it through the left ventricle into the aorta. 



