412 DISEASES OF CATTLE. 



This case differed from the preceding in that all appearance of lung 

 tissue was gone from the diseased mass. Only on the exterior the lung 

 tissue could be recognized, although even there it had been largely con- 

 verted into very dense whitish connective tissue inclosing the fungoid 

 growth. In the other case the external form of the lung and the shape 

 and outline of the lobules were preserved, but the lung tissue itself was 

 not recognizable as such. In the case first mentioned the changes were 

 still less marked, and actinomycosis would not have been suspected by 

 a simple inspection. These few illustrations suffice to show that actino- 

 mycosis of the lungs may appear under quite different forms, and that 

 the nature of the disease can be accurately determined only by finding 

 the fungus itself. Barely actinomycosis attacks the body externally in 

 places other than the head and neck. Crookshank describes the case 

 of a bull in which the flank was attacked and subsequently the scrotum 

 became diseased. A large portion of the skin of the flank was destroyed 

 and covered with a leathery crust. When this was pulled away the pus 

 beneath it showed the actinoinyces grains to the naked eye. 



Actinomycosis may in some cases be confounded with tuberculosis. 

 The diagnosis does not offer any difficulties, since the presence of the 

 aetinomyces fungus at once removes any existing doubts. As has 

 already been intimated, these grains are visible to the naked eye, and 

 their nature is readily determined with the aid of a microscope. 



The course of the disease is quite slow. As the tumors grow they 

 may interfere with -the natural functions of the body. According to 

 their situation, mastication, rumination, or breathing may be interfered 

 with, and in this way the animal may become emaciated. Actinomy- 

 cosis of the jawbones leads to destruction of the teeth and impedes the 

 movements necessary to chewing the food. Similarly, when the disease 

 attacks the soft parts of the head obstructions may arise in the mouth 

 by an inward growth of the tumor. If tumors exist in the pharynx 

 they may partially obstruct the movements necessary to breathing, or 

 close the air-passages and cause partial suffocation. Actinomycosis of 

 the tongue, in interfering with the many and varied movements of this 

 important organ, is also a serious matter. There is no reason to sup- 

 pose that the localized disease interferes with the general health in any 

 other way than indirectly, until internal organs, such as the lungs, 

 become involved. 



Prevention. The question as to how and where animals take this 

 disease is one concerning which we are still in the stage of conjecture, 

 because we possess as yet very little information concerning the life 

 history of the aetinomyces itself. The quite unanimous view of all 

 observers is that animals become infected with the food. The fungus 

 is lodged upon the plants and in some way enters the tissues of the 

 head, the lungs, and the digestive tract, where it sets up its peculiar 

 activity. It is likewise quite generally believed that the fungus is, as 

 it were, inoculated into the affected part. This inoculation is performed 



