MALARIA 235 



or C. oviforme. It is most frequently found in the epithelium of the bile ducts. 

 It has very rarely been reported for man. In these cases (about five) cysts of the 

 liver have been found containing coccidia. The parasite is about 40 X 20^, and is 

 oval in shape with a double outlined integument. The sporozoites, which form 

 inside, are falciform 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 3oX is/*. In the faeces 

 the form most often found is the oocyst, about 40 X 2O//. Infection takes place by 

 ingestion of the oocyst. 



Isospora bigemina. This parasite, formerly called the Coccidium bigeminum, 

 lives in the intestinal villi of dogs and cats. It is about 12 X 8ft. and shows a highly 

 refractile envelope (oocyst) containing two biscuit-shaped sporocysts within each of 

 which are four sporozoites. It has been reported for man three times. 



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 

 (Hsemamceba relicta; this organism is usually designated 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 development 

 in the mosquito from observing that flagellated bodies only appeared some time 

 after the blood was withdrawn. 



Ross (1895) demonstrated that flagellation takes place in the stomach of the 

 mosquito. McCallum (1897) saw fertilization of macrogametes by microgametes 

 of Halteridium. Opie recognized differences in sexual characteristics. 



Ross (1898) demonstrated life cycle of bird malaria (Proteosoma), showing for- 

 mation of zygotes and presence of sporozoites in salivary glands. Grassi and Big- 

 nami proved the cycle for Anophelinae for human malaria. In 1900 (Sambon and 

 Low), infected mosquitoes from Italy were sent to London, where, by biting, they 

 infected two persons. 



Life History. When man is at first infected by sporozoites we have 

 starting up a nonsexual cycle which is completed in from forty-eight to 

 seventy-two hours, according to the species of parasite. The falciform 

 sporozoite bores into a red cell, assumes a round shape and continues 

 to enlarge (schizont). Approaching maturity, it shows division into a 

 varying number of spore-like bodies. At this stage the parasite is 



