Treatment. 877 



to have now and then produced a lasting improvement in 

 leukemia of man. In human medicine relatively the best results 

 have so far been obtained from arsenic and with the Rontgen 

 rays or with both combined. 



Literature. Berndt, A. f. Tk., 1889. XV. 300. — Bollinger, Schw. A., 1871. 

 XXIV. 272. — Cadiot & Weil, Eev. gen., 1905. V. 571. — Ehrlich, Lazarus & 

 Pinkus, Die Aniimie, Wien 1898. — Giittlicli, Pr. Mt., 1880/81. 19. — Johne, S. 

 B., 1879. 24. — de Jong, V. A., 1903. CLXXIII. 511. — Leisering, S. B., 1858. 35; 

 1861. 45; 1865. 29. — Lellmann, B. t. W., 1904. 699. — Lowit, Kongr. f. innere 

 Med. in Karlsbad. 1899. — Luoet, J. vet., 1891. 570. — Noeard, Be la Leueo- 

 cythemie ehez les animaux dom., 1881 (Lit.) ; A. d'Alf., 1882. 361. — Olt, D. t. W., 

 1899. 197. — Pr. Mil. Vb., 1899-1908. — Siedamgrotzky, S. B., 1876. 21; Vortr. 

 f. Tzte., 1878. H. 10 (Lit.). — Stockman, J. of Gomp. Path., 1893. 65. — Wolff, 

 B. t. W., 1892. 121. — Zell, T. E., 1888/89. 49. 



(b) Leukemia of Chickens. 



Leukemia of chickens is an affection of the blood-forming 

 organs, caused by an infection, and is associated with a con- 

 siderable increase and infiltration of large mononuclear leuco- 

 cytes, atrophy of the tissues of the bone marrow, and an in- 

 crease of the myeloid tissue in the liver. The circulating blood 

 frequently shows a diminished number of red blood corpuscles, 

 and also a variable increase of white blood corpuscles. 



History. Although Moore had already in 1896 described "an 

 infectious leukemia of chickens," these cases represented undoubtedly 

 a bacterial, acute infectious disease with a simple hyperleucocytosis, 

 which is frequently met in various infectious diseases of chickens. The 

 cases described by Butterfield (1905), and Yutaka Kon (1907), are 

 more likely to belong to leukemia, although the blood of the affected 

 birds, was not examined. Ellermann & Bang (1908) were the first 

 to recognize and study the disease as such. Valuable studies relative 

 to this disease in its clinical aspect were furnished by Hirschfeld 

 & Jacob (1907), also by Skiba (1909). 



Occurrence. The disease occurs exclusively among chickens, 

 and among these in an enzootic and even an epizootic form. 

 The disease was discovered by Ellermann & Bang in Denmark, 

 and it has also been observed in Grermany (Hirschfeld & Jacoby, 

 Eber). 



Etiology. The disease is produced by some kind of an 

 infectious substance, the nature of which is still unknown. 

 Only this much is known from the investigations of Ellermann 

 & Bang that the cell-free filtrate from organ-emulsions may 

 transmit the disease, and therefore the etiological role of an 

 ultra-visible microorganism does not appear excluded. Hirsch- 

 feld & Jacoby however up to the present always obtained nega- 

 tive results with filtrates through Berkefeld filters of organ 

 emulsions of leukemic chickens. 



The virus is present in all affected organs, the spleen, liver, 

 bone marrow, etc. The infectious properties of the organs, 

 however, are lost in a few days. 



