8 
parasites and the formation of an ookinet which entered the intes- 
tinal epithelium, became encysted, was cast off in the feces and 
served, when ingested by another frog, to propagate the parasite. 
Liihe believes this observation to be in error and regards the 
oocyst as coccidial in nature. The multiple infections of protozoa 
(flagellates, coccidia, and hsemogregarines) found in frogs, often in the 
same animal, renders it very difficult to determine positively to which 
parasite certain phases in the life cycle belong. 
A recent observation by Durham® upon the life history of Dre- 
pamdmm in a South American toad is of special interest. He found 
that nearly all the toads were infested with a species of tick. In 
the stomach of the tick were seen forms of the Drepanidium appar- 
ently in copulation, also peculiar cysts 60 micra in diameter, which 
he believed to be some stage in the life cycle of the parasite. Dur- 
ham regards the tick as the probable intermediate host, although 
this is not definitely established. 
The studies of Billet^ and also some recent observations of Laveran 
and Xegre^^ seem to indicate that trypanosomes may pla}^ a part 
in the life cvcle of LanJcesterella and other haemogregarines. Bevond 
question, a great deal of work is necessary upon this group before 
many doubtful points can be clarified. 
H^MOGREGARINID.^: OF SNAKES AND LIZARDS. 
Liilre^ mentions nineteen species affecting the red blood cor- 
puscles of snakes and lizards. He divides them into two genera, 
Karyolysus and Hsemogregarina. A noteworthy peculiarity of the 
former is the existence of large and small trophozoites (without 
intermediate stages) — the macro-merozoites and micro-merozoites. 
Schizogony takes place in red blood cells in the capillaries of internal 
organs. The membrane remaining after destruction of the red cell 
forms a sort of a cyst wall. The schizonts are of two types, macro- 
schizonts and micro-schizonts, corresponding to the two varieties of 
merozoites. 
« Durham, H. E.: Drepandiinn in the toad. Liverpool School of Tropical Medi- 
cine, Memoir VII — Report of the yellow-fever expedition to Para, Liverpool, 1902, 
pp. 78-79. 
& Billet, A.; Sur le Trypanosoma inopinatum de la grenouille verte de I’Algerie 
et sa relation possible avec les Drepanidium. C. R. Soc. Biol., Paris, vol. 57, Xo. 27, 
1904, pp. 161-165. 
c Laveran, A., & Xegre: Sur un protozoaire parasite de Hyalomma aegyptium. C. 
R. Soc. Biol., Paris, vol. 58, no. 21, 1905, pp. 964-966. 
d Ltilie, M.: In Handbuch der Tropenkrankheiten, C. Mense, Leipzig, 1906, Bd, 
III, pp. 209-210. 
