POULTRV DISEASES AND THEIR TREATMENT. 63 



If the post-mortem fuulings agree in essentials with those giv- 

 en in the preceding paragraphs we may be practically certain 

 that we are dealing with tnberculosis. It should not be forgot- 

 ten, however, that the pathologist would not be willing to pro- 

 nounce the disease tuberculosis until he had taken a small parti- 

 cle of the cheesy material and after staining this in a particular 

 way liad demonstrated by microscopical examination that the 

 tubercle bacilli were present. 



Moore and Ward have carried on some experiments in the 

 use of tuberculin in detecting this disease. Ward (loc. cit.J gives 

 the results of trials on 21 hens affected with tuberculosis. In 

 very few cases did the tests give positive results and these 

 were so slight and irregular as to be useless as a method of diag- 

 nosis. Apparently there is little hope of success in this direc- 

 tion with fowl tuberculosis. 



Methods of Contagion. The spread of tuberculosis from 

 fowl to fowl takes place only when the living bacteria are trans- 

 ferred from the diseased to the healthy birds. From the fact 

 that tuberculous lesions are most commonly found in the inter- 

 nal organs of the digestive system we may conclude that the 

 bacteria usually enter the body along wath the food. Exam- 

 ination of the tubercles situated along the intestine shows that 

 in many cases these communicate directly with the interior of 

 the digestive tract. These are constantly emptying enormous 

 numbers of bacteria which are carried to the outside by the 

 feces of the bird. Without doubt the ilroppings of tuberculous 

 fovi-ls are the most important factor in the spread of this disease. 

 This is especially true when in addition the birds are fed upon 

 ground which is partly covered with these droppings. Besides, 

 the infectious material may very easily be carried by the feet 

 and thus mixed with the food. 



Ward states that there is no e.vidence to indicate that tuber- 

 culosis is spread through the egg. He cites in support of this the 

 fact that badly diseased birds do not lay and second the absence 

 of tuberculosis among young stock. Koch and Rabinowitsch. 

 however, on the basis of later and more thorough work make 

 the following statement (p. 431) : "The possibility of the con- 

 genital origin of tuberculosis of fowls through the infection of 

 the fertilized egg with bird tuberculosis is shown by our results. 

 It is also demonstrated by oiu- inoculation experiments on 



