TISSUE LESIONS 325 



in the filamentous form. In an organ such as the liver, multiple 

 foci of suppuration are seen at the spreading margin of the lesion, 

 often presenting a honeycomb appearance, whilst the colonies 

 of the parasite may be seen in the pus with the naked eye. In 

 the older parts the abscesses have become confluent, and formed 

 large areas of suppuration. 



In cattle the tissue reaction is move of a formative type, there being 

 abundant growth of granulation tissue, which may result jn large tumour- 

 like masses, usually of more or less nodulated character, and often con- 

 sisting of well-developed fibrous tissue containing areas' of younger 

 formation, in which, however, irregular abscess formation maybe present. 

 The cells immediately around the colonies are usually irregularly rounded, 

 or may even be somewhat columnar in shape, whilst farther out they 

 become spindle-shaped and concentrically arranged. It is not uncommon 

 to find leucocytes or granulation tissue invading the substance of the 

 colonies, and portions of the parasite may be contained within leuco- 

 cytes or within small giant-cells, which are sometimes present. A 

 similar invasion, of old colonies by leucocytes is sometimes seen in human 

 actinomycosis. The disease usually remains quite local, or spreads by 

 continuity. It may produce tumour-like masses in the region of the jaw 

 or neck, or it may specially affect the palate or tongue, in the latter pro- 

 ducing enlargement and induration, with nodular thickening on the 

 surface — the condition known as "woody tongue." 



Origin and Distribution of Lesions. — The lesions in the 

 human subject may occur in almost any part of the body, the 

 paths of entrance being very various. In many cases the 

 entrance takes place in the region of the mouth — probably 

 around a decayed tooth — by the crypts of the tonsil, or by 

 some abrasion. Swelling and suppuration may then follow in 

 the vicinity and may spread in various directions, the bones 

 often becoming affected. In a considerable number of cases 

 the primary lesion is in some part of the intestine, generally the 

 large intestine, and not infrequently in connection with the 

 appendix. A peculiar affection of the intestine has been 

 described, in which slightly raised plaques are found both in 

 the large and small intestines, these plaques being composed 

 almost exclusively of masses of the actinomyces along with 

 epithelial cells. This, however, is a rare condition. The path 

 of entrance may also be by the respiratory passages, the primary 

 lesion being pulmonary or peribronchial ; extensive suppuration 

 in the lungs may result. Infection may occur by the skin 

 surface, and lastly, by the female genital tract, as in a case 

 recorded by Grainger Stewart and Muir, in which both ovaries 

 and both Fallopian tubes were affected. 



When the parasite has invaded the tissues by any of these 

 channels, secondary or " metastatic " abscesses may occur in 



