SYMPTOMS 543 



circumscribed tumor the size of a hen's egg or larger. These 

 authors did not determine the histological classification of the 

 tumor. 



REFERENCES 



1 . Beebe and Ewing. a study of the so-called infectivus lym- 

 phosarcoma of dogs. The /our. Med. Research, Vol. XV (1906)^ 

 p. 209. 



2. Smith and Washburn. British Medical Journal, Dec. 17, 

 1908. 



FOWL PEST. 

 Synonyms. Vogelpest; Hnhner-pest; exudative typhus. 



§ 433. Characterization. This is a very acute and 

 rapidly fatal disease of fowls caused by an ultra-microscopic 

 organism that passes through the Berkefeld and Chamberland 

 filters. Pigeons succumb to inoculation. Guinea-pigs and 

 mice are susceptible. 



§ 434. History. In 1880, Rivolta and Delprato differ- 

 entiated a disease from chicken cholera which they designated 

 ''exudative typhus." Perroncito called it a typical fowl 

 cholera. It was investigated and described by Lode and 

 Gruber in 190 1. It was found in the Tyrol where during the 

 time from March until July it had attacked 2,300 hens with a 

 mortality of from 80 to 95 per cent. Centanni described this 

 disease and the nature of its virus. He states that it has been 

 recognized as a distinct affection for more than ten years. 



§ 435. Geographical distribution. It has appeared in 

 Belgium and the Tyrolean Alps and a few other places in 

 Europe. 



§ 436. Etiology. This disease appears to be due to an 

 invisible microorganism. The blood or aqueous suspension 

 of crushed lungs or liver will usually produce the disease when 

 injected in very small doses. It was found by Maggiora that 

 4 cc. of a dilution of virulent blood in which the blood was 



