262 SCIENCE PROGRESS 



mice obtained in London. However, I know that L. muris 

 has been found in England. 



The fauna of the New World has been less examined for 

 protozoal parasites than that of the Old World, but this 

 deficiency in our knowledge is now being supplied. So far 

 as mammalian Leucocytozoa are concerned, Miller (1908) re- 

 corded Hcpatozoon pemiciosum (probably a virulent form of 

 L. muris) from white rats at Washington, and Theobald Smith 

 (1895) found Leucocytozoa in turkeys. 



Among the Amphibia, Carini (1907) recorded L. ranarum 

 which occurs in a South American frog (Leptodactylus 

 ocellatus). 



From Australia, Cleland has recorded Leucocytozoa from the 

 blood of rats in Perth, Western Australia. 



From the above it will be seen that the Leucocytozoa are 

 distributed over a very large area of the world, though there 

 are many tracts from which none have yet been recorded. 

 This would seem to indicate that these highly specialised 

 parasites have been in existence for a long time, and the fact 

 that in many cases they are not fatal to their hosts also 

 points in the same direction. 



We may now note the systematic zoological position of 

 animals harbouring Leucocytozoa. 



The chief hosts of Leucocytozoa among mammals are car- 

 nivores and rodents. The chief carnivores are various breeds 

 of dogs and the Madras bazaar-cat. The rodents are more 

 numerous. They include various rats, white mice, Indian 

 hares, and the Indian palm squirrel. 



Numerous Leucocytozoa have been found in the blood of 

 birds. The chief hosts are the great tit, the raven, the magpie, 

 various species of owls and crows, the Congo grey hawk, the 

 capercailzie, the Scotch grouse, the pheasant, the turkey, the 

 Abyssinian guinea-fowl, and the Francolin partridge. These 

 avian hosts of Leucocytozoa have been found in many parts of 

 the world. 



In the case of mammalian Leucocytozoa the general effect 

 upon the host seems to be that of producing leucocytosis. 

 Patton worked this out carefully in the case of L. funambuli. 

 Miller stated that there was marked anaemia in the case of 

 his infected rats, and considered that the parasite was fatal to 

 them. This is the only case in which much mortality among 



