66 BACTERIOLOGY 



of whicli may cause a very fatal form of meningitis so-callec 

 " leptothrix infection "). The influenza bacillus is extremely 

 delicate, and is probably transmitted from case to case mostly 

 by the inhalation of the fine spray produced on coughing anc 

 sneezing, or even speaking. The Bordet-GrengOU Bacillus 

 now believed to be the cause of Whooping-Cough, is ar 

 organism of somewhat similar type to the influenza bacillus. 



B. anthracis. Anthrax, Splenic Fever, or Splenic Apo 

 plexy, so called from the enlargement of the spleen, is importan 

 as being the first disease in which the specific activity of ! 

 bacterium was studied and demonstrated. It is a very fata 

 septicaemic disease in cattle, whilst sheep, horses, swine, goats 

 deer, and other animals are less frequently attacked. Labora 

 tory animals such as guinea-pigs, rabbits, and mice are very sus 

 ceptible. From any of these it can be communicated to man 

 who is usually infected by handling the carcases or their pro 

 ducts, such as blood, flesh, hides, hair, wool, etc. The bacillu 

 is of large size, 5 to 12 ft or even more in length and T25 ft ii 

 breadth. It is non-motile, with somewhat square or evei 

 slightly concave ends, and in culture tends to form long thread 

 or chains, and is strongly Gram-positive (see Frontispiece 

 fig. 9). Very resistant oval spores are formed by this bacillu 

 (see Fig. 10), and these can retain their vitality for months o 

 even years. Within the living body spores are not usuall; 

 formed, but they occur very readily after death. As the diseasi 

 is a septicaemia, the organism is spread throughout the whoL 

 blood and tissues of the animal. 



In man the commonest clinical forms of the infection are : (1 

 Malignant Pustule of the skin, commencing as a red pimp! 

 which soon becomes a vesicle or little bleb, and then a pustule 

 This may dry up and form a dark, brownish-black scab, fron 

 which the name Anthrax (Latin : anthrax, black) is derived 

 There is usually intense swelling of the surrounding parts 

 (2) Wool-Sorters' Disease, due to inhalation into the wind 

 pipe and larger air-passages of particles of infected hair o 

 wool. (3) Septicaemic Form, resembling that seen in cattle 



The bacillus grows easily in all the ordinary culture-media 

 giving a growth with a very characteristic, wavy, wisp-like out 

 line if on the surface ; and, if grown in the substance of i 

 medium such as gelatin or agar, often producing a fir-tree 

 like branching or " spiking " as it is called. Gelatin is slowb 

 liquefied 



Bacillus diphtheriae. This very important organism, th 

 cause of Diphtheria, belongs to a large group of which it it 



