LIFE-HISTORY OF THE PARASITES OF MALARIA. 571 



Diagrams illustrating the Life-history of the 

 Parasites of Malaria. 



by 



Ronald Ross, D.P.II., Itl.R.C.S., 



Lecturer in Tropical Medicine, University College, Liverpool ; 

 and 



R. Ficldiiig^-Ould, M.A., M.B., 



Acting Demonstrator, Liverpool School of Tropical Medicine. 



With Plates 30 and 31. 



The parasitology of the red blood-corpuscle of Vertebrates 

 was opened in 1870 by Kay Lankester^s discovery of the 

 Drepanidium ranarum. In 1880 Laveran made the 

 important obsei'vation that somewhat similar intra-corpus- 

 cular organisms exist in the blood of human beings suffering 

 fi-om malarial fever. vSince 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 anintra-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 mam- 

 malia (?) ; minute pear-shaped intra-corpuscular bodies^ 



