GEOGRAPHICx\I< DISTRIBUTION 253 



S 189. History. In the fall of 1893, Prof. Samuel 

 Cushman of the Rhode Island State Experiment Station sent 

 a few specimens of the diseased organs of turkeys which had 

 died of "black head" to the Bureau of Animal Industry where 

 they were carefully examined by Dr. Theobald Smith. In the 

 summer of 1S94, Dr. Smith made a careful study of this 

 disease at the Rhode Island Experiment Station. He found 

 that it was caused b>- one of the protozoon ( Amoeba mclcagridis 

 Smith) and he published a full description of the disease 

 which, in accordance with the lesions, he designated Infectious 

 entero-liepatHis. 



In 1895, the disease was further investigated respecting 

 the mode of transmission of the infecting protozoa. The 

 results showed that it could be transmitted directly from 

 diseased to healthy turkeys without the intervention of an 

 intermediate host. These results were published in 1896. 

 Recently, Chester of the Delaware Agricultural Experiment 

 Station has shown that a very similar disease attacks chickens. 

 The place and the time of the first appearance of this disease 

 are not clearly stated, but it seems that New England was the 

 first to suffer from it. 



§ 190. Geographical distribution. The available data 

 bearing upon the geographical distribution of this disease 

 indicate that it is widely distributed. The New England 

 states, particularly Rhode Island, and certain districts in the 

 middle and western states are affected. It has not yet been 

 reported from the southern states. For want of statistics the 

 amount of loss to the poultry industry occasioned by this 

 disease can not be accurately estimated, but the fact that it 

 has caused many farmers and poultry men in New England to 

 discontinue the raising of turkeys shows that it is of much 

 economic importance. It is stated in the report of the Rhode 

 Island Experiment Station for 1894 that "the eradication of 

 this disease would be worth hundreds of thousands of dollars 

 to the eastern farmers alone. ' ' These heavy losses in the east, 

 together with the accumulating evidence that the entire 

 northern third of this country is sprinkled with infected dis- 

 |-ricts from which the disease is spreading, indicate that this 



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