172 BACTERIA 



disease is considered typhoid fever. The test may be either with 

 a hanging drop and examined microscopically, or macroscopically 

 by adding a drop of diluted serum to fresh bouillon culture of 

 typhoid bacilli, when, if the case is typhoid, large clumps of the 

 bacilli will form and drop to the bottom of the tube. Animals 

 immunized against typhoid exhibit this reaction to a high degree. 

 Serum diluted with 10,000 parts of water has caused the reaction 

 in less than one hour's time. This reaction with a known culture 

 of typhoid bacilli is used clinically to identify serum from a doubt- 

 ful case of typhoid, and establish a diagnosis. On the other hand, 

 a known serum prepared artificially by immunizing rabbits with 

 bacilli is used to identify typhoid bacilli when found in water, 

 or elsewhere. There are two stages to the reaction; immediately 

 after mixing the serum and culture, the bacilli will be seen to 

 become less motile, and then still. After this they begin to 

 huddle together into clumps. In complete reaction they remain 

 immobile and tightly massed. In some cases bacteriolysis occurs, 

 and many of the bacteria are dissolved in the serum. The foetus 

 of a woman suffering from typhoid contains agglutinins in its 

 blood. The milk, tears, and other body fluids from an individial 

 with typhoid, agglutinate typhoid bacilli. Serum to perform the 

 test may be obtained by puncturing the skin, or by blistering it 

 and drawing off the serum, or else by abstracting blood from a 

 vein with a hypodermic syringe. 



Agglutinin appears during typhoid, generally after the fifth day, 

 and persists for some time (several years?) after convalescence, 01 

 if the actual agglutinin titer be not high in an immune person, il 

 rises rapidly should typhoid bacilli gain entrance to the body. 

 In persons vaccinated against the germ, the agglutinin titei 

 remains partly high for at least six months but when the amounl 

 shall have returned to normal, it has the power to revive rapidb 

 should infection threaten. Agglutinins are in a measure ai 

 index of resistance, or at least their facility of action is 01 

 guarantee of protection. 



