PLASMODIUM VIVAX 93 



sometimes in the bone marrow, &c. ; this is therefore the cause, 

 of the well-known pigmentation of the spleen in persons who have 

 suffered from malaria. 



The entire increase by schizogony takes place in the circulating 

 blood and occupies seventy-two hours. The blood corpuscles 

 attacked become neither enlarged nor pale. If suitable methods 

 for staining are used one succeeds in demonstrating in all stages 

 the nucleus in the plasmodium as well as the stages of segmenta- 

 tion of the nucleus in schizogony. 



It is very seldom that in examining the blood of persons 

 suffering from quartan fever one comes across other forms (spheres, 

 polymitus). 



The appearance of quartana duplex or triplex is explained 

 by the circumstance that two or three generations of parasites, 

 with a difference of twenty-four hours in their development, are 

 present in the blood. Irregularities in the duration of the 

 development of the parasites obscure the regular character of the 

 disease. 



2. Plasmodium vivax (Grassi and FeL). 



Syn . : Hcemamceba vivax, Gr. et FeL, 1892 ; Plasmodium, var. tertiana, 

 Golgi, 1889 ; Hcemamceba Laverani, var. tertiana, Labbe, 1894 ; Plasmodium 

 tertianum, Labbe, 1899. 



This species is the cause of spring tertian fever ; it is distin- 

 guished from Plasmodium malarice first, by the shorter period 

 (forty-eight hours) occupied in schizogony ; secondly, by the greater 

 activity of the amoeboid movements which do not even cease on 

 being exposed to room temperature, and by the fact that many 

 of the melanin-bearing stages are visible ; moreover, the affected 

 blood corpuscles become enlarged and lose their colour. 1 The stages 

 of schizogony are rarely found in the circulating blood, but fre- 

 quently occur in the spleen. During the process there is no wheel- 

 like arrangement of the merozoites, which lie in a roundish heap 

 about the pigment residue ; they are smaller than those of Plas- 

 modium malaria and are fifteen to twenty in number. The spheres 

 that come under observation in this type attain a size double that 

 of a red blood corpuscle, and are plentifully supplied with coarse 



1 On staining according to Romanowsky's method a peculiar stippling of the 

 affected blood corpuscles appears (Schiiffner, Deutsch. Arch. /. kl. Med., 1899, Ixiv.. 

 p. 428; Maurer, C. f. B., P.^ii /., 1900, xxviii., p. n_i). 



