DIAGRAMS ILLUSTRATING THE LIFE-HISTORY 
OF THE PARASITES OF MALARIA* 
By RONALD ROSS, D.P.H., M.R.C.S. 
Lecturer in Tropical Medicine, University College, Liverpool ; and 
R. FIELDING-OULD, M.A., M.D. (Oxon.) 
Assistant Lecturer, Liverpool School of Tropical Medicine. 
With Plates 
The parasitology of the red blood-corpuscle of vertebrates was opened in 1870 
by Ray Lankester's discovery of the Drepanidium ranarum. In 1880 Laveran 
made the important observation that somewhat similar intra-corpuscular organisms 
exist in the blood of human beings suffering from malarial fever. Since then 
Danielewsky, Kruse, Koch, Dionisi, and others have demonstrated allied parasites 
in the blood of reptiles, birds, bats, and monkeys, and Smith and Kilborne have 
shown that the disease of oxen called Texas cattle fever is due to an intra-corpuscular 
parasite of another kind. As the result of these observations we are now familiar 
with a considerable number of such organisms. All of them are usually classed 
among the protozoa, and in the somewhat artificial order of the sporozoa. They 
are generally divided into three groups, which are as follows : — 
Group I The parasite of Texas cattle fever, Pyrosoma (or Apiosoma) 
bigeminum, Smith and Kilborne, and similar organisms found in dogs and some 
other mammalia (?) ; minute pear-shaped intra-corpuscular bodies, which are known 
to be communicated among oxen by the cattle tick, BoOphilus bovis. 
Group II Organisms apparently allied to the Gregarinidae ; found in reptiles ; 
numerous species. 
Group III Intra-corpuscular amoebae or myxopods found in man, monkeys, 
bats, birds, and possibly frogs. Four species are known to undergo further develop- 
ment in gnats. 
Reprinted from The Quarterly Journal of Microscopical Science. 
