322 BACTERIA AND DISEASE 



Here mention can only be made of the most outstanding facts 

 concerning the disease. It is caused by the "ray fungus," or 

 Streptothrix actinomyces, one of the higher bacteria which, growing 

 on certain cereals, may gain entrance to the tissues of man and beast 

 by lacerations of the mucous membrane of the mouth, by wounds, or 

 by decayed teeth. Barley has been the cereal in question in some 

 cases. The result of the introduction of the parasite is an " infective 

 granuloma." This is, generally speakiug, of the nature of an inflam- 

 matory tumour composed of round cells, epithelioid cells, giant cells, 

 and fibrous tissue, forming nodules of varying sizes. In some cases 

 they develop to large tumours, in others they soon break down. 

 Actinomycosis resembles tuberculosis in some of its tissue characters. 



In the discharge or pus from human cases of the disease small 

 sulphur-yellow bodies may be detected, and these are tufts of " cliubs " 

 which are the broken-down rays of the parasite ; for in the tissues 

 which are affected the parasite arranges itself in a radiate manner, 

 growing and extending at its outer margin and degenerating behind. 

 In cattle the centre of the old ray becomes caseated, or even calcified. 

 In the human disease abundant " threads " are formed as a tangled 

 mass in the middle of the colony. As clubs characterise the bovine 

 actinomycosis, so threads are the feature of the human form of the 

 disease. But in both there is a third element, namely, small round 

 cells, called by some spores, by others simply cocci. They are 

 probably formed from the filaments, but authorities are not yet 

 agreed as to the precise signifioai^ce and r6le of these round cells. 

 The life-history of the micro-organism may be summed up thus: 

 "The spores sprout into excessively fine, straight or sinuous, and 

 sometimes distinctly spirilliform, threads, which branch irregularly 

 and sometimes dichotomously. The extremities of the branches 

 develop the club-shaped bodies. The clubs are closely packed 

 together, so that a more or less globular body is formed, with a central 

 core composed of a dense mass of threads " (Crookshank). (Plate 13, 

 p. 140.) 



In man the disease manifests itself in various parts according 

 to the point of entrance. It has occurred in the mouth, vertebrae, 

 oesophagus, intestine, liver, kidneys, lungs, etc. "When occurring in 

 the mouth, it attacks the lower jaw most frequently. In one recorded 

 case the disease was localised to the bronchi, and did not even extend 

 into the lungs. It was probably contracted by inhalation of the 

 parasite. The disease may spread to distant parts by means of the 

 blood stream (metastatic abscesses), and frequently the abscesses are 

 apt to burrow in various directions. The chronic inflammatory 

 change usually ends in suppuration. 



In the ox the disease remains much more localised, is more 

 formative, and frequently occurs in the lower jaw, palate, or tongue. 



