168 



EXPERIMENTAL INOCULATIONS 



Method of sterilizing Debove's syringe. Withdraw the plunger as far as possible, 

 raise the lever to relax the spring and allow expansion of the glass cylinder. Place 

 the syringe and needle in a vessel of cold water and heat to boiling for 15 or 20 

 minutes. Let the syringe cool ; then take it out of the water with a pair of sterile 

 forceps, let the water above the plunger run out, lower the lever and fit the needle 

 on its socket. 



(When the syringe has been used for an injection., rinse it out in cold water to 



wash out all albuminoid matter which 

 would coagulate on boiling and boil it 

 in the same water, so that both the latter 

 and the syringe are sterilized at the same 

 time. ) 



The syringe may be sterilized in the 

 autoclave if preferred : it is prepared as 

 above and then heated to 115 C. for a 

 quarter of an hour. In most cases, boiling 

 is sufficient to completely sterilize it, but 

 when it has been used for inoculating cul- 

 tures of spore- bearing bacilli, such as B. 

 tetani, B. maligni oedematis, etc., it should 

 be autoclaved. 



Syringes with glass pistons. Malassez 

 has had a syringe made by Luer which, 

 is entirely of glass. The piston itself con- 

 sists of a calibrated glass rod. Numerous 

 forms of syringes based on this pattern 

 can now be bought at a low price. 



These syringes are easily sterilized quite water-tight and are excellent in 



every way, particularly for small volumes (1-2 c.c.). 



Apparatus for injecting large quantities of fluid. In immunizing animals, 

 with toxins when large quantities of filtered cultures are inoculated, syringes 

 are not large enough, and moreover the fluid cannot be injected sufficiently 

 slowly. In these cases the following arrangement 

 is useful (fig. 137). 



The liquid to be inoculated is poured into a tall 

 glass vessel graduated on the glass from above 

 downwards and closed with an india-rubber plug 

 which is perforated by two glass tubes, one of 

 which, reaching to the bottom of the vessel, has a 

 needle attached to its upper end with india-rubber 

 tubing. The other tube passes a few centimetres 

 below the stopper, is plugged with wool, and 

 through it the air in the vessel can be compressed. 

 When this is done the liquid flows out of the 

 needle, and the rate of flow can be regulated at 

 will. 



The apparatus is sterilized in the autoclave 

 and then the liquid to be inoculated aspirated 

 into the vessel. 



FIG. 136. Another reliable form of syringe 

 (" The Record "). 



FIG. 137. Apparatus for inocu- 

 lating large volumes of liquids. 



(ii) Needles. 



Steel needles are very generally used for inocu- 

 lations. The disadvantage of steel is that it so 

 readily rusts with the result that the lumen of the needle soon becomes ob- 

 structed. This difficulty is overcome by carefully washing the needles after 

 use, and keeping them after they have been sterilized by boiling in a small 



