YELLOW FEVER. 



401 



tinal cavity. In the latter it is never found. The isola- 

 tion of the specific microbe was only possible in 58 per 

 cent, of the cases, and in some rare instances may be ac- 

 complished during life. 



The bacillus, at first sight, presents nothing morpho- 

 logically characteristic. It is a small bacillus with 

 rounded ends, generally united in pairs in the culture 

 and in small groups in the tissues. It'is 2-4^ in length, 

 and, as a rule, two or three times longer than broad (Fig. 

 in). It is pleomorphous, and has flagella. By em- 

 ploying suitable methods it can be found in the organs 



FIG. in. Bacillus icteroides (Sanarelli). 



of yellow fever cadavers, usually united in little groups, 

 always situated in the small capillaries of the liver, kid- 

 ney, etc. The best method of demonstration is to keep 

 a fragment of liver, obtained from a body soon after 

 death, in the incubator at 37 C. for twelve hours and 

 allow the bacteria to multiply in the fresh tissue before 

 examination. 



The bacillus can be cultivated upon the ordinary 

 media. Upon gelatin plates it forms rounded, transpar- 

 ent, granular colonies, which during the first three or 

 four days present somewhat the appearance of leukocytes. 



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