266 



BACTERIOLOGY. 



obtained by this procedure are more rapid and are far 

 more dangerous than a subcutaneous injection. 



The injection is made by means of the syringe or injec- 

 tion apparatus, described above. Special care must be 



taken to see that all air-bubbles 

 are expelled from the syringe 

 before it is used. Air in itself 

 is not dangerous, provided it is 

 not injected rapidly and in large 

 bubbles. It is well, therefore, 

 to begin the injection as slowly 

 as possible. 



The rabbit is the animal 

 employed most often for this 

 method of injection. This is 

 due to the fact that the mar- 

 ginal branch of the posterior 

 auricular vein is easily entered 

 with the needle. With a little 

 FIG. 44. The Voges cylindrical holder, practice the operation can be 



for guinea-pigs. n , 



done almost as expeditiously as 



an ordinary subcutaneous injection. It is well to select an 

 animal with white ears, and in which the marginal vein is 

 fairly large. Occasionally this vein is very narrow and it 

 is then extremely difficult to enter. It is advisable, more- 

 over, to use a sharp new needle. 



The animal is placed on the table before a window. The assistant 

 holds the animal down gently but firmly. One hand rests over the pel- 

 vis, the other covers the head and holds the front leg's. There is 

 really but one vein in the rabbit's ear which can be used for the pur- 

 pose of injection. The large, middle veins of the ear are imbedded in 

 loose connective tissue, and hence, readily roll away from the needle. 

 The posterior marginal vein is narrow, but it is imbedded in such a 

 manner that it cannot move away. Hence, little difficulty is experi- 

 enced in penetrating this vein although it may seem to be narrower 

 than the needle. 



By means of a pair of scissors, preferably bent, the hair is re- 

 moved from the surface over this marginal vein. A piece of cotton, 



