ACTINOMYCOSIS 451 



and " Mycetomata," in which the grains are formed by thicker 

 mycelial filaments, segmented, and with a well-defined membrane. 



Actinomycosis 



Actinomycosis in man clinically and pathologically 

 closely resembles tuberculosis, with which in the past it 

 was frequently confounded. 



Actinomycosis in cattle has long been known, but its 

 exact pathology was involved in considerable doubt until 

 the researches of Bellinger in 1876. It forms tumours 

 chiefly affecting the tongue, jaw, face, and throat, and 

 was described under such varied names as wen, scrofula, 

 scirrhus, osteo-sarcoma, cancer, wooden tongue, etc. 



The tumours after a time break down and discharge, 

 the tongue often protrudes from the mouth, the saliva 

 drips, and the animal becomes much emaciated. 



On cutting into a " wooden tongue," or wen, a grating 

 sensation is felt, such as that experienced in cutting a 

 turnip or unripe pear ; on examining the section little 

 rounded, yellowish, frequently almost caseating areas will 

 be noticed, resembling old tubercles. On making sections 

 and examining with a low power, these rounded areas are 

 found to be composed of masses of small round-cells, with 

 occasionally giant-cells, surrounded by a capsule of fibrous 

 tissue. The growth may be so soft as to be practically 

 purulent, and abscesses varying in size from a pin's head 

 to that of an orange may be present in the affected areas. 

 Like tubercles, the growths may become caseous, calcified, 

 or fibrous. In the growth or in the pus from abscesses, 

 when examined fresh with a low power, yellowish or 

 yellowish- white granules will be found here and there, 

 which may be very minute, or as large as a small pin's head, 

 are somewhat soft in consistence, and on slight pressure 

 flatten out. Examined with a high power, these granules 



