THE TYPHOID BACILLUS. 



stain the dry cover-glass preparation at a moderate 

 heat. Good results are also obtained if the cover- 

 glass is kept for twenty-four hours in cold carbolic 

 fuchsine solution which has been diluted with three 

 parts of water. 



The flagella of the typhoid bacilli can be very 

 beautifully stained, if to the ordinary mordant exactly 

 ly of caustic soda solution be added. Great care must 



/o 



be taken in measuring this quantity, as the flagella 

 are very much affected even by slight variations in 

 this respect. They are very long, and there are great 

 numbers of them all over the body. (Fig- 8, Plate 

 II.). It is not easy to render them visible. It is best 

 for this purpose to use agar-agar stroke cultures, 

 which are only five hours old, and which have been 

 kept at blood heat in an incubator. It is true that 

 where the cultures are older, the £agella are more 

 easily stained, but then, on the other hand, they are 

 frequently thrown off from the bacteria, when they are 

 seen to be dispersed irregularly in great numbers 

 throughout the preparation. For further details see 

 Chapter XI. 



Neither is it quite easy to demonstrate this bacillus 

 in the human body. It is best for this purpose to 

 make thin sections of the intestine. When consider- 

 able numbers of bacilli are present, which is not 

 the case in every stage of the disease, they will be 

 seen to occur either collected together in small clumps 



