DISEASES AND PARASITES OF FOWLS 379 



membrane and wall of the intestine on the inner side of the 

 tubercle breaks down and discharges the contents of the 

 tubercle into the foecal matter that is passing through the 

 intestine, thus carrying out with the excreta a great num- 

 ber of living tubercle bacilli. 



' ' The liver is the other organ commonly affected. When 

 the tubercle bacillus finds its way into the liver and begins 

 to grow, a yellowish spot is soon formed, increasing in size 

 as the disease progresses. The structure of the tissue at 

 this point is changed to a hard granular mass containing 

 within it the bacilli and the same substance as found in the 

 intestinal tubercle. The growth of the tubercles necessarily 

 increases the size of the liver until it sometimes becomes 

 twice its normal size, and the tubercles are frequently so 

 numerous as to give the liver the appearance of peanut 

 taffy. 



" There are other spots of similar appearance sometimes 

 found on the liver that must not be mistaken for tubercles. 

 A crude way of distinguishing tubercular lesions is by the 

 fibroid tissue of a tubercle being tougher and harder than 

 the structure of the other spots mentioned, and by the 

 center being filled with a substance as before described. 

 Sometimes the disease is scattered all through the internal 

 organs, and tubercles may be found even on the heart." 

 Fernet. 



The only certain method of diagnosing the disease is a 

 bacteriological examination. The germ is a small organism 

 measuring on an average 3/25000 of an inch in length and 

 can only be seen through a microscope. Poultrymen should 

 avail themselves of the services of the bacteriologist of the 

 experiment station if they are suspicious of this disease in 

 their flocks. Many of the stations have facilities for doing 

 this work without charge. 



It is not definitely known that bovine or human tuber- 



