PATHOGENIC BACTERIA. 315 



sists of a severe acute inflammation of the colon, frequently 

 with necrosis of the surface and the formation of pseudo- 

 membrane. Ulceration may occur, but is usually superficial. 

 Duval and Bassett found the bacillus of dysentery in the 

 stools of infants having summer diarrhoea. 



The introduction of pure cultures into animals by way of 

 the alimentary canal has sometimes been followed by a cer- 

 tain amount of diarrhoea, but it does not appear that dysen- 

 tery, as it occurs in man, has been reproduced. Most labor- 

 atory animals are, however, very sensitive to the injection 

 into the tissues or veins of cultures, living or dead. They 

 show the lesions produced by many toxins. 



The bacillus is agglutinated by the patient's blood, but 

 often only late in the disease and apparently not in all cases. 

 This test seems to have only a limited value in clinical diag- 

 nosis. Many prefer to secure the reaction in a test-tube. 

 The dilutions used vary greatly (from i in 20 to I in 100). 

 Immunized animals develop the agglutinins in the blood. 

 The outlook for a curative serum is encouraging. 



It now seems that the bacillus of Shiga has numerous 

 close allies, constituting with it a " group." To what extent 

 the others of the group may be concerned in the causation 

 of diarrhoeal diseases, or may occur in the normal intestine 

 is uncertain. According to W. H. Park some of these form 

 indol and develop acid from mannit, which the bacillus of 

 Shiga does not; they also differ from it in their agglutina- 

 tion reactions. 1 



Spirillum cholerae (Comma bacillus of cholera). A rod- 

 or staff-shaped organism, somewhat curved, and with 



1 Shiga, Ccntralblatt f. Baktcriologic, Bd. XXIV., 1898; Flexner, 

 Philadelphia Medical Journal, September I, 1900; Vedder and Duval, 

 Journal Experimental Medicine, Vol. VI.; Gay, University of Pennsyl- 

 vania Medical Bulletin. November, 1902; Duval and Bassett, American 

 Medicine, 1902, Vol. IV., p. 417; Park and Carey, Journal Medical Re- 

 search, Vol. IX., 1003; Strong and Mtisgrove, Journal American Medical 

 Association, Vol. XXXV., 1900, ). 498. 



