INFECTIOUS DISEASES OF CATTLE. 435 



because we possess as yet very little information concerning the life 

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

 observers is that animals become infected from the food. The f ungus 

 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 generally believed that the fungus is, as it 

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

 by the sharp and pointed parts of plants which penetrate the mucous 

 membrane and carry with them the fungus. The disease is therefore 

 inoculable rather than contagious. The mere presence of the diseased 

 animal will not give rise to disease in healthy animals unless the acti- 

 nomyces grains pass directly from the diseased into some wound or 

 abrasion of the healthy or else drop upon the food which is consumed 

 by the healthy. Not only are these views deducible from clinical 

 observation, but they have been proved by the positive inoculation of 

 calves and smaller animals with actinomyces. The danger therefore 

 of the presence of actinomyces for healthy animals is a limited one. 

 Nevertheless an animal affected with this disease should not be 

 allowed to go at large or run with other animals. If the fungus is 

 being scattered by discharging growths we certainly can not state at 

 this stage of our knowledge that other animals may not be infected by 

 such distribution, and we must assume, until more positive informa- 

 tion is at hand, that this actually occurs. 



It is, however, the opinion of the majority of authorities that when 

 actinomycosis appears among a large number of animals they all con- 

 tract it in the same way from the food. Much speculation has there- 

 fore arisen whether any particular plant or group of plants is the 

 source of the infection and whether any special condition of the soil 

 favors it. Very little positive information is at hand on these ques- 

 tions. It would be very desirable for those who live in localities 

 where this disease is prevalent to make statistical and other observa- 

 tions on the occurrence of the disease with reference to the season of 

 the year, the kind of food, the nature of the soil (whether swampy or 

 dry, recently reclaimed or cultivated for a long time) tspon which the 

 animals are pastured or upon which the food is grown. 



It is highly probable that such investigations will lead to an under- 

 standing of the source of the fungus and the means for checking 

 the spread of the disease itself. Veterinarian Jensen, of Denmark, 

 made some observations upon an extensive outbreak of actinomycosis 

 a number of years ago, which led him to infer that the animals 

 were inoculated by eating barley straw harvested from pieces of 

 ground just reclaimed from the sea. While the animals remained 

 unaffected as long as they pastured on this ground or ate the hay 

 obtained from it, they became diseased after eating the straw of 

 cereals from the same territory. Others have found that cattle grazing 

 upon low pastures along the banks of streams and subject to inunda- 



