SPOROZOA IN GENERAL 279 



blood cells of birds. \>ry little is known regarding the life-cycle 

 and method of transmission of the members of this genus. Many 

 species have been named but largely on the basis of host rather 

 than on morphological differences. Hartman (1927) has studied 

 leucocytozoa from birds in this country. 



Hsemogregarines are unpigmented parasites that occur in both 

 red and white cells in the peripheral blood of mammals, birds, 

 amphibia, and fish. Species most easily obtained for study belong 

 to the genera Laiikcsfcrella and Karyolysiis; these occur in the 

 blood of frogs. An excellent account of a mammalian hsemo- 

 gregarine is that of ]\Iiller (1908) who studied Hcpatozoon muris, 

 the asexual stages of which occur in rats and the sexual stages in 

 the rat mite. Another ha^mogregarine that has been described 

 in detail is Hccuiogrcgarina stcpaiwici (Reichenow, 1910) which 

 occurs in the tortoise and the leech. Hsemogregarines have been 

 described from man but, as Wenyon (1923) has pointed out, 

 these probably were abnormal specimens of other parasites, or 

 artifacts. 



The family piroplasmid^ contains several species that are 

 available for study in certain parts of America. One of these is 

 the parasite of Texas fever in cattle, Babesia bigcuwia. This 

 species, as Smith and Kilbourne (1893) proved, is transmitted by 

 ticks and passes by "heredity'' from the mother tick by way of her 

 eggs to the young ticks. The life-cycle of this organism in the 

 tick is unknown. Dogs, monkeys and many other domesticated and 

 wild mammals have been found to be infected with species of 

 Babesia to which separate specific names have been given. The 

 species in the dog, Babesia eanis, is probably better known than 

 that in any other mammal. 



Certain genera have been described in the order h.^mosporidia 

 that are doubtful in nature. Toxoplasma has been reported from 

 various species of mammals and birds and even from man. 

 Cytauia^ba bacterifera is an organism that occurs frequently in 

 the red blood cells of frogs in the United States and other coun- 

 tries. Its nature and systematic position are doubtful (Hegner, 

 1921). Alinute spherical bodies that appear near the margin of 

 the red cells of cattle and other animals, both in this country and 

 abroad, have been considered by various investigators to be pro- 

 tozoa and placed in the genus Aiiaplasma. They appear to consist 

 almost entirely of chromatin. They may not even represent living 



