262 



BACTERIOLOGY. 



In the above procedure, the hair is removed from over the desired 

 area by means of scissors. The spot is then rubbed thoroughly, with 

 a cloth or sponge soaked in mercuric chloride (1-1000) or lysol (2 per 

 cent.). This skin is then raised by the fingers, or with forceps, and 

 the small nick or incision is made. This should extend through the 

 skin. It is advisable to insert the lance or a blade of the scissors 

 under the skin, thus making a pouch. Guinea-pigs and rabbits are 

 inoculated over the side. The animal is held down on the table 

 by an assistant. Mice and rats are inoculated over the root of the 

 tail. The tail of the animal is seized with a pair of rat or crucible 

 forceps (Fig. 46 6, p. 273) and drawn over the edge of the jar. The 

 weighted wire-gauze cover, of the battery jar in which it is confined, 

 is moved slightly to one side so as to allow the tail and lower portion 

 of the body to be drawn out. The tail is held by the left hand while 

 the opening and subsequent inoculation are made with the right. 



Subcutaneous injection is practised by means of a 

 sterile syringe. For this purpose the Koch syring-e has 

 been used extensively, but it cannot be 

 said to possess any marked advantage 

 over a good hypodermic syringe, and, 

 it certainly is less convenient. It is ad- 

 visable to employ a syringe with an 

 adjustable rubber piston. The stem of 

 the piston should be graduated to in- 

 dicate c.c, and should have a set-screw, 

 thus enabling the operator to inject 

 the amount desired with the least 

 trouble or uncertainty. The Roux- 

 Collin syringe, or one such as is shown 

 in Fig. 40, is the most durable and 

 useful of its kind. 



The syringe should be sterilized in 

 boiling water in a water-bath. An 

 enamelled stewing-pan heated by a 

 Fletcher radial burner (Fig. 41, a, b) is an extremely useful 

 accessory in the laboratory. The syringe should not be 

 placed direct in the boiling water. The latter should be 

 drawn up into the syringe and expelled several times in 



Fig. 

 inge. 



40. Adjustable syr- 

 F— Rubber piston. 



