METHODS OF INOCULATION 



143 



FIG. 47. Hollow 

 needle with 

 lateral aperture 

 (at a) for intra- 

 jifi'iloneal in- 

 oculatious. 



between the forefingers and thumbs of the two hands, and 

 the needle is plunged through the fold thus formed. The 

 result is that the hole in the side of the needle is within the 

 abdominal cavity, and the inoculation can thus 

 In- made. Intraperitoneal inoculation can also 

 be practised with an ordinary needle. The 

 mode of procedure is similar, but, after the 

 needle is plunged through the abdominal fold, 

 it is partially withdrawn till the point is felt 

 to be free in the peritoneal cavity, when the 

 injection is made. There is little risk of injur- 

 ing the intestines by either method. 



4. Intravenous Injection. The vein most 

 usually chosen is one of the auricular veins. 

 Tli<- part has the hair removed, the skin is 

 purified, and the vein made prominent by 

 pressing on it between the point of inoculation 

 and the heart. The needle is then plunged into 

 the vein, and the fluid injected. That it has 

 perforated the vessel will be shown by the 

 escape of a little blood ; and that the injection 

 has taken place into the lumen of the vessel will be known by 

 the absence of the small swelling which occurs in subcutaneous 

 injections. If preferred, the vein may be first laid bare by 

 snipping the skin over it. The needle is then introduced. 



". inoculation into the Anterior Gliamber of the Eye. Local 

 anaesthesia is established by applying a few drops of 2 per cent, 

 solution of hydrochlorate of cocaine. The eye is fixed by pinch- 

 ing up the orbital conjunctiva with a pair of fine forceps, and, 

 the edge of the cornea being perforated by the hypodermic needle, 

 the injection is easily accomplished. 



Sometimes inoculations are made by planting small pieces of 

 pathological tissues in the subcutaneous tissue. This is especially 

 dune in the case of glanders and tubercle. The skin over the 

 back is purified, and the hair cut. A small incision is made with 

 a sterile knife, and the skin being separated from the subjacent 

 tissues by means of the ends of a blunt pair of forceps, a little 

 pocket is formed into which a piece of the suspected tissue is 

 inserted. The wound is then closed with a suture, and collodion 

 is applied. In the case of guinea-pigs, the abdominal wall is to 

 br preferred as the site of inoculation, as the skin over the back 

 is extremely thick. 



Injections are sometimes made into other parts of the body, 

 '.'/. the pleurae, the cranium, the spinal canal. With regard to 



