158 PLASMODIUM MALARIiE [CH. 



development is very much prolonged and consequently the 

 mosquito does not become infective until after a much longer 

 incubation period. 



The length of time that a mosquito remains infected has 

 never yet been proved, but it is probably for the remainder of 

 its life. 



Distribution. This species is widely distributed throughout 

 the world, occurring in most tropical and subtropical regions. 

 It also occurs somewhat scantily in Northern Europe below 60° 

 north latitude. 



As a result of successful mosquito campaigns and other 

 prophylactic measures the distribution of the disease is being 

 restricted, and it has been eradicated from some parts of the 

 world. Tertian fever or ague was formerly prevalent in Britain 

 and it is interesting to note that one or two isolated cases 

 of malaria in patients that had never left England have been 

 recorded within the present century. Consequently the con- 

 ditions for the transmission of the disease have not yet entirely 

 disappeared from this country. 



II. Plasmodium malaria (Laveran, 1881) and Quartan Fever. 



Synonyms : Oscillaria malaricB Laveran, 1883. Plasmo- 

 dium var. quartana Golgi, 1890. Plasmodium malarice var. 

 quartancB Celli and San Felice, 1891. Hcemamoeba malaricB 

 Grassi and Feletti, 1892. Hcemamceba laverani var. quartana 

 Labbe, 1894. Hcemosporidium quartance Lewkowicz, 1897. 

 Plasmodium malarice quartanum Labbe, 1899. Hcsmomonas 

 malaricB Ross, 1900. HcBmamceba malarice var. magna Laveran, 

 1900. H. malaria var. quartance Laveran, 1901. Plasmodium 

 golgii Sambon, 1902. Plasmodium quartance Billet, 1904. 

 Laverania malarice Jancs6, 1905. 



Description. The young trophozoite is somewhat smaller 

 than that of P. vivax, and also much less active. The pseudo- 

 podia are usually blunt, so that the parasite is rather com- 

 pact in appearance. The pigment is deposited in the form of 

 very coarse darkly-coloured granules, or rodlets, which are 



