The distribution of the chromatin in the pear-shaped _Babesia_, as seen in _B. canis_ and _B. bovis_, is interesting. The main nuclear body consists of a karyosome surrounded by a clear area. There is also a loose (chromidial) mass of chromatin representing the remains of the chromatin forks seen during the formation of the parasite as a daughter form by gemmation. Occasionally there is a small dot or point, the so-called “blepharoplast” of Schaudinn and Lühe. This minute dot is not a flagellate blepharoplast, for there is no flagellate stage in the life-history of Babesia. These nuclear phenomena have been described by Nuttall and Graham-Smith and Christophers (1907)[214] for _B. canis_, by Fantham (1907)[215] for _B. bovis_, and by Thomson and Fantham (1913) from glucose-blood cultures of _B. canis_. [214] _Sci. Mems. Govt. India_, No. 29. [215] _Quart. Journ. Microsc. Sci._, li, p. 297. Babesia are tick borne, as was first shown by Smith and Kilborne (1893). The developmental cycle in the tick is incompletely known. The best accounts are those of Christophers (1907)[216] for _B. canis_ and Koch (1906) for _B. bovis_, and these accounts are supplementary. The principal stages, so far as known, may be summarized thus:-- [216] _Sci. Mems. Govt. India_, No. 29. (1) The piroplasms taken by the tick in feeding on blood pass into the tick’s stomach. The pyriform parasites, which alone are capable of further development, are set free from the blood corpuscles. In about twelve to eighteen hours they become amœboid, sending out long, stiff, slender, pointed pseudopodia. The nucleus of each parasite divides unequally into two. Similar forms have been obtained in cultures. These stellate forms may be gametes, and according to Koch fuse in pairs. (2) A spherical stage follows, possibly representing the zygote. This grows, and a uninucleate globular mass results. This form is found in large numbers on the third day, according to the observations of Koch. (3) A club-shaped organism is next formed. This may represent an oökinete stage. The club-shaped bodies are motile and gregarine-like, and are about four times the size of the blood forms. These club-shaped bodies and subsequent stages were described by Christophers in the development of _B. canis_ in the dog-tick, _Rhipicephalus sanguineus_. (4) The club-shaped bodies pass from the gut of the tick into the ovary, and so get into the ova. There they become globular, and later are found in the cells of the developing tick-embryo. The parasites are, then, transmitted hereditarily. Similar globular bodies are found in the tissue cells of the body of tick nymphs which have taken up piroplasms. The globular stage was called the “zygote” by Christophers, but it may correspond to the oöcyst of Plasmodia.