3l6 BACTERIA 



perature. Pfeiffer's bacillus appears most abundantly at 

 the height of the disease, and disappears with convalescence. 

 It is said not to appear in any other disease. 



Yellow Fever. Sternberg and Havelburg have both 

 isolated bacilli from cases of yellow fever; but the organism 

 discovered by Sanarelli, the Bacillus icteroides^ is now ac- 

 cepted as the causal agent of the disease. It is a small, 

 short rod, with round ends, and generally united in pairs; 

 it has various pleomorphic forms; it grows well on all the 

 ordinary media; it is killed in sea- water at 60° C, and also 

 by direct sunlight in a few hours. 



Diarrhoea of Infants. From time to time different 

 organisms have been isolated in this diseased condition. 

 Bacillus coli and B. enteriditis sporogenes (Klein) have been 

 held responsible for it. W. D. Booker, of Johns Hopkins 

 University, sums up an extended research into the question 

 as follows : 



" No single micro-organism is found to be the specific exciter 

 of the summer diarrhoea of infants, but the affection is generally 

 to be attributed to the result of the activity of a number of 

 varieties of bacteria, some of which belong to well-known species, 

 and are of ordinary occurrence and wide distribution, the most 

 important being the streptococcus and Proteus vulgaris, 



" The first step in the pathological process is probably an injury 

 to the epithelium from abnormal or excessive fermentation, from 

 toxic products of bacteria, or from other factors. 



" Bacteria exert a direct injury upon the tissues in some in- 

 stances, whereas in others the damage is brought about indirectly 

 through the production of soluble poisons." 



Actinomycosis. This disease affects both animals and 

 man. As Professor Crookshank points out, it has long been 

 known in this country,' but its various manifestations have 



^ Bacteriology and Infective Diseases (i8g6), p. 144. Professor Crooksliank's 

 Reports to the Agricultural Department of the Privy Council constitute the 

 most complete account of this disease hitherto published. 



