LAVERANIA MALARIA 167 



The appearance of quartana duplex or triplex is conditional on the 

 presence in the blood of the patient of two or three groups of 

 Plasmodia differing in their development by twenty-four hours. 



The chief distinctive characters of the quartan parasite are : (i) 

 The erythrocyte is unchanged in size ; (2) the rings are compact and 

 show pigment early; in the larger forms the chromatin is dense and 

 relatively plentiful ; (3) the pigment, which is relatively well-marked, 

 may be arranged at the periphery. 



Laverania malariae, Grassi and Feletti, 1890 = Plasmodium 

 falciparum, Welch, 1897. 



Syn. : Plasmodium malaria var. quotidians, Celli et Sanf., 1891 ; Hcemamceba 

 malarice prcecox, Gr. et Fel., 1892 (nee H. prcscox, Gr. et Fel., 1890) ; Hcemamoeba 

 lave rani, Labbe, 1894 ; Htzmatozoon falciparum, Welch, 1897 ; Hcemosporidium 

 undecimance and H. sedecimance. and H. vigesimo-tertiance, Lewkowitz, 1897 ; Hcema- 

 maeba malaria parva, Lav., 1900 ; Plasmodium prcecox, Dofl., 1901 ; Plasmodium 

 immaculatum, Schaud., 1902 ; Plasmodium falcipamm, Blanch., 1905. 



The names most commonly used for the parasite of malignant 

 tertian malaria are Plasmodium falciparum and Laverania malarice. 



The summer and autumn fever (febris aestivo-autumnalis), also 

 called malignant tertian or sub-tertian, is caused by a malarial parasite 

 which is distinguished by the small size of its schizont, while the 

 gametocytes are crescentic (figs. 81, 88). 



Most authors identify this kind of fever or the parasites which cause it (Laverania 

 malarice) with the pernicious malaria of the tropics. Ziemann, however, repeatedly 

 has drawn attention to certain small but definite differences between the usual malig- 

 nant tertian or pernicious parasites which occur in the tropics and the tropical parasites 

 of some malarial districts, particularly of West Africa, and insists that at least two 

 varieties or sub-species occur. Other investigators distinguish from this or these 

 forms a quotidian parasite. On the other hand, the assertion is made that there are 

 no specific differences, but that the malignant or pernicious tertian parasite which 

 normally needs forty-eight hours for its development in the blood of man, can 

 also develop in twenty-four hours. The establishment of the duration of the 

 development is a matter of especial difficulty, because the stages of schizogony 

 are far less numerous in the peripheral blood than in that of the internal organs. It 

 is also stated that the tropical parasite very seldom forms crescentic but rather 

 rounded gametocytes. According to such an observation the organism would belong 

 to Plasmodium and not to Laverania. The question whether the tropical fevers are 

 caused by two different parasites does not seem to be definitely settled. 



The young trophozoite of the malignant, pernicious tertian, or sub- 

 tertian parasite (fig. 87) are but slightly active and are very small, even 

 after the formation of the comparatively large food vacuole, which 

 makes the body appear annular ("signet ring" stage). Often two and 

 even more parasites are found in one blood corpuscle. 



Fully grown they only attain two-thirds or less of the diameter of 

 the erythrocytes, which display an inclination to shrink and then appear 



