ANTHRAX 149 



matory secretion of the urethra, both in the cells (Fig. 27, b) and in the fluid. 

 Thence it spreads to the epithelium and mucous glands, and finally to the 

 other parts of the genital system. It may even extend all over the body 

 (gonorrhoeal rheumatism). The cocci lie usually in pairs, the stained cells 

 being separated by a clear unstained line where the mutually flattened sides 

 are in contact. They are non-motile, and about the same size as staphylo- 

 cocci, from which, however, they are readily distinguishable by the paired 

 grouping of the cells. None of the above-mentioned cocci are known to 

 form spores. 



A not infrequent cause of inflammation and suppuration in human 

 beings is the ' Pneumococcus ' (Diplococcus pnenmoniae) of Frankel, the usual 

 cause of pneumonia (130). 



2. ANTHRAX (131) (Figs. 28, d\ 27, c; 5, e, 7; n, a, g\ 29). The 

 anthrax bacillus (B. anthracis) was discovered about the middle of the pre- 

 sent century (in the early fifties) in the blood of cattle suffering from splenic 

 fever. It was detected in the form of colourless, motionless rods lying about 

 between the blood-corpuscles. Although from the first suspected to be 

 the morbid agent, proof was not available until many years afterwards 

 (1863). Through Koch's investigations into the life-history of the organism, 

 anthrax or splenic fever has found its way into all the text-books as-a clas- 

 sical example of a bacterial infection. Koch followed the process of spore 

 formation, and obtained the first pure cultures of the bacillus, commencing 

 with this work his brilliant career as the founder of modern bacteriological 

 technique. * 



The anthrax parasite is a comparatively large bacillus, cylindrical in 

 shape, 3-6 /u, long by 1-5 p. thick, varying within certain limits, as all bac- 

 teria do. Both in the blood and in the tissues single cells and cell-chains 

 occur (Fig. 27, c}. In cultures the growth is chiefly filamentous, the plate 

 colonies being as a result fringed with shaggy edges, loops, and curls of 

 filaments stretching out into the gelatine. For the same reason stab cul- 

 tures have a bristly appearance. The cells are non-motile, but form spores 

 readily *. 



The anthrax bacillus grows well in artificial cultures, but needs good 

 sources of nitrogen and carbon ; it is a peptone bacterium. There is, 

 however, no doubt that it is not an obligatory parasite, but metatrophic, for 

 it has been observed to grow well and form spores in cow-dung and earth. 

 This indicates how the disease may arise in cattle, which are much more 

 subject to infection than human beings. In man, infection generally takes 

 place from skin wounds, and the disease remains localized, rarely spreading 

 to other parts. In cattle, on the other hand, it is with food that the 



* With regard to spore formation, see p. 20; germination, p. 22 ; resistance to heat, p. 76; 

 dryness, p. 77 ; poisons, p. 82 ; degeneration and attenuation, p. 28. 



