336 



PROTOZOOLOGY 



lum is discarded; cysts unobserved; in young turkeys, chicks, grouse, 

 and quail. Bayon and Bishop (1937) successfully cultured the organ- 

 ism from hen's liver. Morphology of the cultured forms (Bishop, 

 1938). 



This organism is the cause of enterohepatitis known as "black- 

 head," an infectious disease, in young turkeys and also in other 

 fowls, in which it is often fatal. Smith (1895) discovered the organ- 

 ism and considered it an amoeba (1910). It invades and destroys the 

 mucosa of the intestine and caeca as well as the liver tissues. Tropho- 



Fig. 136. a, Mastigamoeba hylae, X690 (Becker); b, Actinomonas 

 mirabilis, XI 140 (Griessmann) ; c, Dimorpha mutans, X940 (Blochmann); 

 d, e, Tetradimorpha radiata CHsiung) (d, a typical specimen, X430; e, 

 swimming individual, X300); f, Pteridomonas pulex, X540 (Penard); g, 

 Rhizomastix gracilis, X1340 (Mackinnon). 



