SERUM DIAGNOSIS 119 



sons possesses the agglutinating property for typhoid 

 germs. It is less marked, however, than in those in- 

 fected with typhoid, and, therefore, in making the test 

 the blood-serum is diluted to about i to 50, when the 

 agglutinating power (of any but the typhoid blood) is too 

 attenuated to manifest itself. 



Method of Application. The lobe of the ear having 

 been cleaned with bichlorid, lysol, or other antiseptic, 

 followed by sterile water, a deep puncture is made with 

 a sterile needle or other pointed instrument. A small 

 amount of blood is collected either in a capillary tube 

 or upon a sterile cover-glass. The blood or, preferably, 

 the serum portion is diluted with normal salt solution or 

 broth to i to 25, then a drop of this dilution is mixed 

 with an equal amount of young vigorous typhoid germs 

 from a broth culture, placed in hanging-drop beneath 

 the microscope, and observed. 



Should the test be positive, in from one-half to two 

 hours the bacilli will be seen to clump together into 

 masses and lose their motility. The test may be made 

 without the use of the microscope by mixing the culture 

 and serum in a test-tube, when at the end of the usual 

 time a flocculent precipitate will be observed to form in 

 the mixture. 



TYPHOID OPHTHALMO-REACTION 



This test is similar to the tuberculin ophthalmo- 

 reaction. A solution of J to J mg. of "typho-protein," 



