CHAPTER X. 



'^ MALARIA. 



Not a disease of bacterial origin — Beasons for believing the Plasmodmm 

 mala/rim to be the specific cause of the disease — Distribution and 

 occurrence — Forms of the malarial parasite — Evolution of the 

 organism — Flagellated and oreseentic bodies — Mosquito theory — 

 Varieties of the malarial parasite — Quartan, tertian, malignant 

 tertian, and quotidian fevers — Morphological characters of varieties 

 — Examination of the blood for the parasites — Stained blood 

 preparations. 



Malaria is not a disease of bacterial origin, as was at first 

 thought by many investigators, but the exciting cause is a 

 protozoon, and is usually called the Plasmodium malarice. 

 It has also been known as the Hcematozoon or Rcem-aTnosba 

 malaria, because it is found in the blood. It was first 

 shown by Laveran, in the year 1880, that certain pig- 

 mented organisms were to be found in the blood of 

 malarial patients ; and as one of the forms described by 

 him was crescent-shaped, they received the name ' Laveran's 

 sickles.' It has since been found that this particular 

 organism described by him occurs chiefly after an attack of 

 malarial fever, and is not necessarily present in the blood 

 during the febrile period. Later on it began to be recog- 

 nised that the varying forms of malarial fever are each 

 caused by distinct varieties of parasites. 



The following are the reasons for believing the Plas- 

 Tnodium malarice to be the specific cause of malaria : 



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