DISTRIBUTION OF THE SPIRILLA. 379 



of large cocci, often staining faintly. All these changes in 

 appearance are to be classed together as involution forms. 



Staining. Cholera spirilla stain readily with the usual 

 basic aniline stains, though Loffler's methylene-blue or 

 weak carbol-fuchsin is specially suitable. They lose the 

 stain in Gram's method. 



Distribution within the Body. The chief fact in this 

 connection is that the spirilla are confined to the intestine, 

 and are not present in the blood or internal organs. This 

 was determined by Koch in his earlier work, and his state- 

 ment has been amply confirmed. In cases in which there 

 is the characteristic " rice-water " fluid in the intestines, they 

 occur in enormous numbers almost in pure culture. The 

 lower half of the small intestine is the part most affected. 

 Its surface epithelium becomes shed in great part, and the 

 flakes floating in the fluid consist chiefly of masses of 

 epithelial cells and mucus, amongst which are numerous 

 spirilla. The spirilla also penetrate the follicles of Lieber- 

 kiihn, and may be seen lying between the basement mem- 

 brane and the epithelial lining, which becomes loosened by 

 their action. They are, however, rarely found in the 

 connective tissue beneath, and never penetrate deeply. 

 Along with these changes there is congestion of the mucosa, 

 especially around the Peyer's patches and solitary glands, 

 which are somewhat swollen and prominent. In some very 

 acute cases the mucosa may show general acute congestion 

 with a rosy pink colour, but very little desquamation of epi- 

 thelium occurs, the intestinal contents being a comparatively 

 clear fluid containing the spirilla organisms in large numbers. 

 In other cases of a more chronic type, the intestine may 

 show more extensive necrosis of the mucosa and a consider- 

 able amount of haemorrhage into its substance, along with 

 formation of false membrane at places. The intestinal 

 contents in such cases are blood-stained and foul-smelling, 

 there being a great proportion of other organisms present 

 besides the cholera spirilla (Koch). 



Cultivation. (For Methods, see p. 399). 



The cholera spirillum grows readily on all the ordinary 





