MALARIA. 185 



stage it lives within an epithelial cell, which it destroys. Afterward 

 it falls into the lumen lined by this epithelial cell and sporulates, either 

 by the method of schizogony or sporogony. 



Eimeria stiedae. This sporozoon is usually known as the 

 Coccidium cuniculi or C. oviforme. It is most frequently found in the 

 epithelium of the bile ducts. It has very rarely been reported for man. 

 The parasite is about 40 x 2o//, and is oval in shape with a double 

 outlined integument. The sporozoites, which form inside, are falci- 

 form in shape. These escape and enter fresh epithelial cells, and thus 

 the process of schizogony goes on. The parasites of the liver are 

 larger than those found in the intestines, these latter being only about 

 30 x i5//. In the faeces the form most often found is the oocyst, about 

 40 x 25//. 



Isospora bigemina. This parasite, formerly called the Coccidium 

 bigeminum, lives in the intestinal villi of dogs and cats. It is about 

 12 x 8fjL, and shows a highly refractile envelope containing two 

 biscuit-shaped spores. It has been reported for man. 



Haemosporidia. 



Of the sporozoa found in the blood (Haemosporidia), the malarial 

 parasites are the only ones connected with disease in man. 



In addition to man, infections with parasites of a similar nature are 

 found in monkeys (Plasmodium kochi; the sexual forms alone seem 

 to be present), in birds (PL praecox; this infection is usually desig- 

 nated Proteosoma. An infection of crows and pigeons of like nature is 

 Halteridium). Numerous haemosporidia have been reported for bats, 

 various other mammals, tortoises, lizards, etc. 



The life history of the malarial parasite is one of the most interesting 

 chapters in medicine. Laveran discovered the parasite in 1880. In 

 1885, Golgi noted that sporulation occurred simultaneously at time of 

 malarial paroxysm. Koch, Golgi and Celli demonstrated existence of 

 different species for different types of fever. King and Laveran (1884) 

 considered possibility of mosquito transmission. Manson (1894) 

 formulated hypothesis that gametes were destined to undergo develop- 

 ment in the mosquito from observing that flagellated bodies only ap- 

 peared some time after the blood was withdrawn. 



