470 BACTERIOLOGY. 



necessary to test carefully the limits of its agglutinating 

 power for each variety. When this is done it will be 

 found that the serum of an animal immunized with the 

 Shiga type of organism will agglutinate that type of 

 organism in high dilutions, say 1 : 5000, while the 

 Harris type of organism will only be agglutinated in 

 dilutions of 1 : 200, and the Hiss-Russell type of organ- 

 ism in dilutions of 1 : 50. On the other hand, the serum 

 of an animal immunized with the Flexner type of or- 

 ganism will agglutinate that type of organism in high 

 dilutions, say 1 : 10,000, while the other two types of the 

 organism will be agglutinated only in dilutions of 1 : 1 00. 

 The serum of an animal immunized with the Hiss- 

 Russell type of organism will agglutinate that type of 

 organism in dilutions, say of 1 : 1000, while the Harris 

 type is agglutinated only in dilutions of 1 : 100, and the 

 Shiga type in dilutions of 1 : 20. 



PROTECTIVE INOCULATION. By the repeated inocu- 

 lation of animals with cultures of this organism, killed 

 either by heat or by chemicals, it has been found pos- 

 sible to protect them against otherwise fatal doses of the 

 living virulent organism. When treated in this way, 

 the goat supplies a serum that exhibits not only an 

 agglutinating power over the living bacilli, but pos- 

 sesses both protective and curative properties when in- 

 jected into other susceptible animals. 



During 1898-1899 Shiga 1 employed a protective 

 serum, made after the foregoing principles, in the treat- 

 ment of dysentery in human beings. During the period 

 mentioned he treated 266 cases, and had a death-rate of 



1 See " The Epidemic Dysentery of the Past Twenty Years in Japan," 

 by Stuart Eldridge, M. D., U. S. Marine-Hospital Service, Public Health 

 Reports, 1900, vol. xv., No. 1, pp. 1-11. 



