BIOLOGICAL THERAPEUTICS 



555 



movements are difficult to control. This test is being studied carefully by 

 the bureau with a view to its more extensive employment in area work. 

 Directions for the Application of the Intradermal Test. 



1. Various sites may be selected for the intradermal injections. 

 The sites most used are the subcaudal region and the skin of the lower 

 eyelid. The injections should be made with a hypodermic syringe pro- 

 vided with a needle about one-fourth inch in length and of small caliber. 

 The syringe and needles used generally by the dental profession are sat- 

 isfactory, but many operators prefer a moderately large syringe with 

 adapters for the use of the dental needle. 



2. The injection should be made into the dermal tissue, care being 

 taken to prevent the tuberculin frim being d scharged into the sub- 

 cutaneous tissue, or superficially into the epidermis. An injection into a 



A Positive Reaction to tlie Intradermal 

 Test for Tuberculosis Indicated by 

 A Diffused Swell.ng 



Positive Reaction to the Intradernaal 

 Test for Tuberculosis Indicated 

 by a Circumscribed Swelling 



loose subcaudal fold is liable to result in the production of an infiltration 

 so slight as to prove of no diagnostic vakie; hence, a more preferable site 

 is the undcTf.urface of the tail, where the soft skin lies close to the bone. 

 The swelTtig or edLina here is more pronounced. In case the eye is 

 selected the iiijecllo'.i is made in the lo'.vi r lid one-fourth inch below the 

 border and about on^'-Iialf inch from the corner of the eye. 



3. Swtlliiigs that apjoear within the first hour and disappear early 

 are not diagnostic. Swellings present at the forty.-eighth hour are gen- 

 erally diagnostic ; hence, observations should be made at the f oriy-eighth 

 and sevenrsecoud hours and, if possible, at a period between the nine- 

 tieth and ninety-sixth hours, or longer. The later the appearance of the 

 local reaction, the more positive the diagnosis. The local reaction is often 

 confirmed by a thermal reaction, this being especially true in those cases 

 in which tuberculin has not been administered recently by the subcutane- 

 ous method. These two methods may be employed simultaneously, well^ 

 defined reactions to botlDJ^*flizd?#i*>Jg MitSXfSdf^m infected animals. The 



