Bacteriologic Diagnosis 649 



Meyer and Bergell* prepared a serum by injecting horses 

 with a new typhoid toxin. After two years' treatment 

 they were able to demonstrate its value in curing infection 

 in laboratory animals, von Leydenj speaks in favorable 

 terms of this serum. 



The typhoid immune (bacteriolytic) serum is specific, but 

 its action requires the presence of additional complementary 

 substance, and by itself it is useless. Indeed, it may do 

 harm by causing the formation of anti-immune bodies. 



So far no serum has been produced that is of any value 

 in therapeutics. 



Bacteriologic Diagnosis. There are four means by 

 which bacteriologic methods may assist the clinician in corn- 



Fig. 224. Typhoid bacilli, tmag- Fig. 225. Typhoid bacilli, show- 

 glutinated (Jordan). ing typical clumping by typhoid 



serum (Jordan). 



pleting the diagnosis of typhoid fever. In the order of their 

 general usefulness and practicability these are: 



1. The Widal reaction of agglutination. 



2. The blood-culture. 



3. The isolation of the bacillus from the feces. 



4. Conjunctival and dermal reactions. 



Widal Reaction of Agglutination. This very valuable 

 adjunct to our means of making the diagnosis of atypical and 

 obscure cases of typhoidal infection was discovered in 1896 

 when Widal and Griinbaum, { working independently, ob- 



* "Med. Klinik," m, No. 31, p. 917, Aug. 4, 1907. 

 f'Berl. klin. Wochenschrift," 1907, No. 18. 

 t "La Semaine Medicale," 1896, p. 295. 



