164 THE ANIMAL PARASITES OF MAN 



The sporozoites of the various malarial parasites show no specific 

 differences. They were stated by Schaudinn to occur in three forms, 

 and these were described as indifferent (neuter), female and male. 

 There is, however, little or no evidence for this hypothetical differ- 

 entiation. The last were said to perish prematurely, that is, in the 

 oocyst. The others after the rupture of the oocysts enter the body 

 cavity of the Anophelines, whence they are carried along in the course 

 of the blood. Finally they penetrate the salivary glands (fig. 80, 27) 

 probably by their own activity, break through their epithelia and 

 accumulate in the salivary duct (fig. 80, 27). At the next bite by the 

 mosquito they are transmitted to the blood-vessels of man. 



THE SPECIES OF MALARIAL PARASITES OF MAN. 



In view of the differences in opinion regarding "species" and "varieties," the dispute 

 whether the malarial parasites of man represent one species with several varieties, or several 

 species is almost superfluous. If necessary two genera may be distinguished. 



The parasites of the tertian and quartan fever are alike in that 

 their gametocytes have a rounded shape (figs. 80, 12, 15), whilst the 

 corresponding stages of the pernicious or malignant tertian parasites 

 are crescentic (figs. 81, 88). These differences are used by some writers 

 as the distinguishing characteristic of two genera : Plasmodium, Mar- 

 chiafava and Celli, 1885, for the first mentioned species ; Laverania, 

 Grassi and Feletti, 1889, for the pernicious or malignant tertian parasite. 

 Whether there is a genuine quotidian fever and accordingly a special 

 quotidian parasite is still disputed. 



These parasites are treated in practical detail in Stephens and Christophers' 

 " Practical Study of Malaria," 3rd edition, 1908. 



Plasmodium vivax, Grassi and Feletti, 1890. 



Syn. : Hamamceba vivax, Grassi and Feletti, 1890; Plasmodium malarice var. 

 tertiance, Celli and Sanfelice, 1891 ; Hcemamosba laverani var. tertiana, Labbe, 

 1894 ; Hcemosporidium tertiamim, Lewkowitz, 1897 ; Plasmodium malarice tertianum, 

 Labbe, 1899: Hcemamceba malarice var. magna, Laveran, 1900, p.p.; Hcemamceba 

 malarice var. tertiance, Laveran, 1901. 



This species, P. vivax? is the causal agent of the simple or spring 

 tertian fever and is, therefore, named directly the tertian or benign 

 tertian parasite (figs. 80, 3-8 ; 85). During the afebrile period in the 

 patient, the young trophozoites or amcebnlae appear on or in the red 

 blood corpuscles as pale bodies of 1-5 //, to 2 //, diameter which at 

 first show only slow amoeboid movements. Their nucleus is difficult 

 to recognize in the early stage. Soon the food vacuole is formed and 

 this grows concomitantly with the trophozoite and the parasite has a 

 ring-like appearance. Afterwards the vacuole diminishes, and at this 



1 See Schaudinn, F. (1902), Arb. a. d. kaiserl. Gesundheits., xix, pp. 169-250, 3 plates. 



