MATERIAL FOR BACTERIOLOGICAL EXAMINATION 225 



made by shaving the skin and rubbing the material onto the 

 shaved surface or scratching with a scalpel or special scarifier, 

 but without drawing blood, and then rubbing in the material 

 to be inoculated. Intracidaneons inoculation is performed 

 with a finer needle than the ordinary hypodermic needle and 

 is made just into the true skin and not thro^igh or under it. 



Subepithelial injections, just between the true skin and the 

 epidermis, are to be preferred to intracutaneous; this is the 

 procedure for the "Schick test" in diphtheria and is being 

 introduced for smallpox vaccination. 



Intravenous injections are made with larger animals. In 

 rabbits the posterior external auricular is a convenient vein. 

 In larger animals the external jugular is used. 



Intraperitoneal, -thoracic, -cardiac, -ocular, -muscular injec- 

 tions, and injections into the parenchyma of internal organs 

 are accomplished with the hypodermic needle. In the case 

 of the first two, injury to contained organs should be care- 

 fully avoided. Intracardiac injection, or aspiration of the 

 heart to seciu-e blood, requires considerable practice to be 

 successful without causing the death of the animal at once 

 through internal hemorrhage. In subdural injections into 

 the cranial cavity it is necessary to trephine the skull first, 

 while such injections into the spinal canal may be accom- 

 plished between the vertebrae with needles longer and 

 stronger than the usual hypodermic needle. Occasionally 

 animals are caused to inhale the organisms, or are fed cultures 

 mixed with the feed. 



SECURING AND TRANSPORTING MATERIAL FROM 

 ANIMALS FOR BACTERIOLOGICAL EXAMINATION. 



If the site of the lesion is readily accessible from the 

 exterior, material from the living animal should be collected 

 with sterile instruments and kept in sterile utensils until the 

 necessary tests can be made. Testing should be done on 

 material as soon after collection as possible, in all cases, to 

 avoid the effects of "decomposition" bacteria. 



If the blood is to be investigated it may be aspirated from 

 a peripheral vein with a sterile hypodermic syringe of appro- 

 priate size or allowed to flow through a sterile cannula into 

 15 



