NOT DESCRIBED IX PREVIOUS SECTIONS. 443 



in large numbers, and death appears to be due to toxaemia rather than 

 to septicaemia. Mice are not susceptible to infection by subcutaneous 

 injections. Small quantities injected beneath the skin of guinea-pigs 

 usually produce a local abscess only ; larger amounts two to five 

 cubic centimetres frequently produce a fatal result, with symptoms 

 and pathological appearances corresponding with those resulting 

 from intravenous injection. These are fever, developed soon after 

 the injection, diarrhoea, and symptoms of collapse appearing shortly 

 before death. At the autopsy the liver and spleen appear normal, or 

 nearly so ; the kidneys are congested and may present scattered 

 purictiform ecchymoses (Weisser). According to Escherich, the 

 spleen is often somewhat enlarged. The small intestine is hyper- 

 aemic, especially in its upper portion, and the peritoneal layer pre- 

 sents a rosy color ; the mucous membrane gives evidence of more 

 or less intense catarrhal inflammation, and contains mucus, often 

 slightly mixed with blood. In rabbits death occurs at a somewhat 

 later date, and diarrhoea is a common symptom. In dogs the subcu- 

 taneous injection of a considerable quantity of a pure culture may 

 give rise to an extensive local abscess. 



Varieties. Booker, in his extended studies relating to the bac- 

 teria present in the faeces of infants suffering from summer diarrhoea, 

 has isolated seven varieties "which closely resemble Bacterium coli 

 commune in morphology and growth in agar, neutral gelatin, and 

 potato, but by means of other tests a distinction can be made between 

 them." These are described as follows : 



BACILLUS d OF BOOKER. 



' ' Found in two cases of cholera inf antum and the predominating 1 form in 

 one serious case of catarrhal enteritis. 



" Morphology. Resembles Bacterium coli commune. 



' ' Growth in Colonies. Gelatin : Colonies grow luxuriantly in gelatin, and 

 thrive in acid and sugar gelatin equally as well as in neutral gelatin. In 

 the latter the colonies closely resemble, but are not identical with, the Bac- 

 terium coli commune. In acid gelatin they differ very much from Bacterium 

 coli commune. The colonies spread extensively and are bluish-white with 

 concentric rings. Slightly magnified, they have a large, uniform, yellow 

 central zone surrounded by a border composed of perpendicular threads 

 placed thickly together. Sometimes a series of these rings appear with inter- 

 vening yellow rings. 



"Agar: The colonies are round, spread out, and blue or bluish- white. 

 Slightly magnified, they have a pale-yellow color. 



' Stab Cultures Gelatin: In sugar gelatin the surface growth has a 

 nearly colorless centre surrounded by a thick border with an outer edge of 

 fine, hair-like fringe ; the growth along the line of inoculation is fine and deli- 

 cate. In neutral gelatin the growth is not so luxuriant as on sugar gelatin ; 

 on the surface it is thick and white, with a delicate stalk in the depth. 



" Agar : Thick white surface growth with a well -developed stalk in the 

 depth. 



"Potato: Luxuriant yellow, glistening, moist, and slightly raised sur- 

 face, with well-defined borders. 



