THE PATHOGENIC HEMOSPORIDIA 277 



thickenings. He did not find more tlian one of these processes from 

 the same cell, but Breinl and Hindle ('08) describe typical flagella, 

 which appear to have no definite or constant place in reference to one 

 another or with the cell. The latter observers, while stating that these 

 "flagella" are formed only during a very transient phase in the life 

 history, do not offer any interpretation in regard to them. Christo- 

 phers ('07) failed to find flagellated forms either in vivo or in vitro. 



Second, as to the so-called "club-shaped bodies" first observed by 

 Nuttall and Graham-Smith ('08) and recently followed out by Chris- 

 tophers in Babesia canis in the tick Rhipicephalus sanguineus. These 

 characteristic bodies have been found only in the insect's body where 

 they give rise by direct metamorphosis to what Christophers does not 

 hesitate to call "zygotes" or fertilized cells, although nothing in the 

 nature of fertilization and nothing resembling gametes were described 

 by him. Two varieties of this club-shaped body are described, one 

 being "rigid, thorn-like," and relatively inactive; the other more 

 "leech-like" and active. Curious disks, with or without short spines, 

 and with the appearance of boring organs, are present at one end. 

 Christophers states that these bodies may reproduce by longitudinal 

 division, the daughter cells remaining attached so as to give the 

 appearance of conjugation. They are found not only in the gut of 

 infected ticks, but also in oviducts, ovaries, and ova of the adult, 

 while in nymphs they may be spread throughout the tissues of the 

 body. The " zygotes" formed by metamorphosis of these club-shaped 

 bodies are intracellular parasites of oval or spherical form, and may 

 grow to the size of 25 /z. The chromatin becomes diffused throughout 

 the cell prior to the formation of reproductive centres which Christo- 

 phers regards as sporoblasts, and the zygote ultimately gives rise to 

 " sporozoites" similar to the intracorpuscular forms in dog's blood. 



Nuttall and Graham-Smith interpreted these club-shaped bodies 

 as gametocytes, a view confirmed by Christophers, whose account 

 certainly suggests a sexual cycle in the tick. If this account is con- 

 firmed, the life history of Babesia canis is very similar to that of plas- 

 modium. The rarity of "flagellated" stages and their occurrence 

 only at late stages of infection certainly point toward Doflein's original 

 view that the "flagella" are microgametes, a view which the majority 

 of subsequent investigators have accepted. Doflein and, later, Kino- 

 shita maintained that there is a cyclical difference between the ame- 

 boid forms and the pyriform bodies, the former representing the 

 schizogonous cycle, the latter the sexual. The prevalence of the 

 piriform bodies at the end of the disease in infected animals, and the 

 formation of "flagella" from them, lends support to this hypothesis. 



Babesia in man gives rise to an acute disease variously designated 

 as "blue fever," "black fever," "tick fever," "spotted fever," "piro- 

 plasmosis hominis," and the like. It appears to be local in distribu- 



