YELLOW FEVER. 



519 



cadavers of yellow fever Sanarelli found them either 

 entirely sterile or universally invaded by certain microbic 

 species, such as the Streptococcus pyogenes, the colon 

 bacillus, the protei, etc., which cannot be the cause of 

 the disease. In the second case he examined he was 

 fortunate enough to find what he is satisfied is the 

 specific microbe, the Bacillus icteroides. In 11 autopsies 

 he never found the organism alone, but always associated 

 with the bacteria mentioned above. The Bacillus icter- 

 oides must be sought for in the blood and tissues, and not 

 in the gastro-intestinal tract. In the latter it is never 



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Fig. 116. — Bacillus icteroides (Sanarelli). 



found. The isolation of the specific microbe was possible 

 only in 58 per cent, of the cases, and in some rare instances 

 may be accomplished during life. 



The bacillus presents nothing morphologically charac- 

 teristic. It is a small pleomorphous bacillus with rounded 

 ends, usually united in pairs in the culture and in small 

 groups in the tissues. It is 2-4 f* in length, and, as a 

 rule, two or three times longer than broad (Fig. 116). 

 The organism is actively motile, and has flagella. 



It does not form spores. It stains by the usual 

 methods, but does not stain by Gram's method. It grows 



