120 BACTERIOLOGY 



an extract of typhoid bacilli, is mixed with a drop of 

 water and instilled into the conjunctival sac of a patient 

 suspected of having typhoid fever. If typhoid be present 

 a typic reaction occurs, which is characterized by hyper- 

 emia and injection of the palpebral conjunctiva of the 

 lower lid and the caruncle. 



In 75 cases of typhoid fever a positive reaction 

 occurred in 71. The reaction takes place within from 

 one to two and a half hours, and persists for from thirty- 

 six to forty-eight hours. The reaction causes no discom- 

 fort and appears to be without danger. It is of recent 

 development and has not yet been widely used, but it 

 promises to be one of the most accurate and least com- 

 plicated of any of the later diagnostic measures. 



THE WASSERMANN TEST FOR SYPHILIS 



This test depends upon hemolysis and the so-called 

 deviation and fixation of complement. The process is 

 most too complicated for practical demonstration in a 

 work of this character, but an endeavor will be made to 

 give such an exposition of the subject as will enable 

 one to understand the principle involved in the test. 



We have learned that when the blood of an animal 

 of one species is injected into an animal of a different 

 species, the blood of the animal injected acquired power 

 of hemolysis (i. e., ability to destroy the corpuscles) for 

 the blood of the species from whence the injected blood 

 came. 



