462 CHOLERA 



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 con- 

 nection is that the spirilla are practically confined to the intestine. 

 Recent observations show that they may be found sometimes in 

 the internal organs, and especially in the gall-bladder and biliary 

 passages, where catarrhal changes may be produced by them. 

 The all-important factor in the pathology of the disease, however, 

 is the absorption of toxins from the bowel. 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 Lieberkiihn, and may be seen 

 lying between the basement membrane and the epithelial lining, 

 which becomes loosened by their action. They are, however, 

 rarely found in the connective tissue beneath. 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 there may be rela- 

 tively little desquamation of epithelium, the intestinal contents 

 being a comparatively clear fluid containing the spirilla in large 

 numbers. In other cases of a more chronic type, the intestine 

 may show more extensive necrosis of the mucosa and a con- 

 siderable 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. 472.) 



The cholera spirillum grows readily on all the ordinary media, 

 and, with the exception of that on potato, growth takes place at 

 the ordinary room temperature. The most suitable temperature, 

 however, is that of the body, and growth usually stops about 

 16 C., though in some cases it has been obtained at a lower 

 temperature. Abundant growth occurs on media with suffi- 

 ciently alkaline reaction to inhibit the growth of many 

 intestinal bacteria, e.g., Dieudonne's medium, p. 44. 



Peptone Gelatin. On this medium the organism grows well 

 and produces liquefaction. In puncture cultivations at 22 C. 



