THE LEUCOCYTOZOA 249 



The earliest known of these Leucocytozoa was that recorded 

 by Danilewsky in 1890 from the blood of an owl. He regarded 

 his " leucocytozaire," however, as a stage in the development 

 of a Polymitus of malaria occurring in the same bird, though 

 he was careful to state that he was far from regarding all 

 Leucocytozoa as stages in the development of some Polymitus. 

 It is now known that the Leucocytozoa and the Polymitus of 

 malaria have no connection. 



Berestneff, Sacharoff, Ziemann, and Laveran also investigated 

 Leucocytozoa in birds, their subjects including various owls, 

 crows and hawks. The parasites resemble closely those 

 described by Danilewsky. Schaudinn (1904) also wrote a paper 

 on a Leucocytozoon from the little owl, and considered it to be 

 a stage in the life-history of a Spirochaete. It is now generally 

 recognised that Schaudinn was dealing with a mixed infection, 

 and that Spirochaetes and Leucocytozoa are distinct organisms, 

 each with its own individual life-cycle. 



Recently Sambon (1907) has published a short note on a 

 Leucocytozoon occurring in the blood of grouse. Similar 

 parasites have been found in other game birds (cf. Sambon, 

 1908-9). 



Among the amphibian forms, the best known Leucocytozoon 

 is L. ranarum (Carini, 1907), a large form from Leptodactylus 

 ocellatus, a South American frog. 



So far as I am aware, no Leucocytozoa, apart from the above, 

 have been recorded as occurring in vertebrates lower than the 

 Mammalia, but there are several mammalian Leucocytozoa which 

 may now be considered. 



Leucocytozoon canis, common in the pariah dogs of India, 

 was described by Bentley and by James in 1905. Later, 

 Christophers (1906-7) worked on the same parasite, and 

 described its stages in the tick that carried the disease from 

 dog to dog. He thus linked a definite vertebrate parasite 

 with an invertebrate host, the latter seemingly being unaffected 

 by the parasite. Patton (1906-7) has described more mammalian 

 Leucocytozoa than any other investigator of the group. He 

 found a parasite in the leucocytes of the Indian palm squirrel 

 {Funambulus pennantii), and named it L. funambuli '; in the blood 

 of dogs (L. cam's) ; in the blood of the bazaar-cat of Madras 

 (L. felis domestical) ; and in that of the Indian hare Lepus nigri- 

 collis (L. leporis). Malay dogs also . contain Leucocytozoa as 



