IX] PLASMODIUM VIVAX 155 



measure in hospitals, where in the absence oi any such pre- 

 caution the dissemination of malaria may result from the 

 bringing together of many cases of the disease. 



DESCRIPTIONS OF THE THREE PLASMODIA CAUSING MALARIA. 



I. Plasmodium vivax (Grassi and Feletti, 1890) 

 and Tertian Malaria. 



SYNONYMS : Oscillaria malaria Laveran, 1881, pro parte. 

 Hcemosporidium tertianum Lewkowicz, 1887. Plasmodium 

 var. tertiana Golgi, 1889. Hcemamceba vivax Grassi and Feletti, 



1890. Plasmodium malarice var. tertiana Celli and San Felice, 



1891. Hcemamceba laverani var. tertiana Labbe, 1894. Plas- 

 modium malarice tertianum Labbe, 1899. Hcemamceba malarice 

 var. magna Laveran, 1900. Hcemamceba malarice var. tertiance 

 Laveran, 1901. Plasmodium tertiance Billet, 1904, pro parte. 



Description. The young trophozoite appears in the red 

 blood corpuscles as a very actively amoeboid body about 

 1-2 /a in diameter. It is much more active than the other 

 two species of malarial parasites and it was because of this 

 feature that the specific name vivax was applied to it. The 

 young trophozoite very . soon assumes the ring form, and by 

 means of its pseudopodia and the large amount of exposed 

 surface, it grows rapidly at the expense of the contents of the 

 red cell. The latter becomes pale and swollen, and on staining 

 with Giemsa its protoplasm presents certain degeneration 

 phenomena, taking the form of scattered red granules, known 

 as Schuffner's dots. The presence of these dots in the proto- 

 plasm of the infected red cells generally serves to distinguish 

 P. vivax from the other malarial parasites, but similar ap- 

 pearances occur in the red cells of dogs infected with Babesia 

 (Piroplasma] canis. 



As the trophozoite grows, melanin is formed and deposited 

 in the form of fine rods scattered throughout the cytoplasm 

 of the parasite. The period of growth occupies about 30 

 hours, by which time the trophozoite almost fills the corpuscle, 

 the fully formed schizont being 8 -5-10^ in diameter. 



