DISTRIBUTION OF LESIONS. 267 



ally the parasite may enter the tissues from the oesophagus. 

 In a considerable number of cases the primary lesion is in 

 some part of the intestine, generally of the large intestine. 

 The parasite penetrates the wall of the bowel, and may be 

 found deeply between the coats, surrounded by purulent 

 material. The affection is followed by ulceration, and 

 sometimes by a considerable amount of necrosis. Thence 

 it may spread to the peritoneum or to the extraperitoneal 

 tissue, the retro-caecal connective tissue and that around 

 the rectum being not uncommonly seats of suppuration 

 produced in this way. 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 acti- 

 nomyces along with epithelial cells. This, however, is a 

 very rare condition. The path of entrance may also be 

 by the respiratory passages, the primary lesion being 

 pulmonary or peribronchial ; and extensive suppuration in 

 the lungs may result. Infection may also occur by the 

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

 case recorded by Sir T. Grainger Stewart and one of us, in 

 which both ovaries and both Fallopian tubes were affected. 



In actinomycosis the abscesses are apt to burrow in 

 various directions, and may open externally, leading to 

 chronic sinuses, which discharge pus in which the parasite 

 may be found. When the parasite has invaded the tissues by 

 any of these channels, secondary or " metastatic " abscesses 

 may occur in internal organs. The liver is the organ most 

 frequently affected, though abscesses may occur in the lungs, 

 brain, kidneys, etc. In such cases the spread takes place 

 by the blood stream, and it is possible that leucocytes may 

 be the carriers of the infection, as it is not uncommon to 

 find leucocytes in the neighbourhood of a colony contain- 

 ing small portions of the filaments in their interior. 



In the ox, on the other hand, 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- 



