CULTIVATION 449 



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 confined to the intestine, and are 

 not present in the blood or internal organs. 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 Lieberkiilm, 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, and never pene- 

 trate 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 

 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 considerable 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. 459). 



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. 

 a whitish line appears along the needle track, at the upper part 

 of which liquefaction commences, and as evaporation quickly 

 occurs, a small bell-sliaprd <lcpression forms, which gives the 

 appearance of an air-bubble. On the fourth or fifth day we get 

 the following appearance: there is at the surface the bubble- 

 29 



