INFECTIOUS DISEASES OF CATTLE. 451 



This case differed from the preceding in that all appearance of 

 lung tissue had disappeared from the diseased mass. Only on the 

 exterior the lung tissue could be recognized, although even there it 

 had been largely converted 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 antinomycosis 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. 

 Rarely 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 actinomyces grains to the naked eye. 



Actinomycosis may also involve the udder, the spermatic cord of 

 castrated animals, vagina, and, when it becomes generalized, the 

 brain, liver, spleen, and muscular tissue. 



Actinomycosis may in some cases be confounded with tuberculosis. 

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

 actinomyces fungus at once removes any existing doubts. As has 

 already been intimated, these grains, simulating sulphur balls, 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 inter- 

 fered with, and in this way the animal ma}^ become emaciated. Acti- 

 nomycosis of the jawbones leads to destruction of the teeth and 

 impedes the movements necessary to chewing the food. Similarly, 

 v/hen the disease attacks the soft parts of the head obstructions may 

 arise in the mouth by an inward growth of the tumor. If tumor- 

 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 

 manv and varied movements of this important organ, is also a serious 

 matter. There is no reason to suppose that the localized disease 

 interferes with the general health in any other way than indirectly 

 until internal organs, such as the lungs, become involved. 



A very small proportion of the cases may recover spontaneously, 

 the tumors being encysted or undergoing calcification. In most cases 



