MALARIA. 377 



At times these also give rise to typical quotidian fever. 

 The different parasites appear to Marchiafava and Celli, 

 however, as varieties of a single parasite. Grassi and 

 Feletti have gone so far as to describe five species. 



As cultivation of the malarial parasites is at present not 

 possible, the question whether the forms of parasites are 

 constant and variable, or whether each form gives rise to a 

 definite type of fever, can only be determined by experi- 

 mental conveyance of the parasites with the blood of 

 malarial patients. Such inoculation- experiments have been 

 repeatedly made in human beings. The results, as sum- 

 marized by Mannaberg, are as follows : Of sixteen care- 

 fully performed experiments, there was in fourteen a com- 

 plete concurrence between the forms of parasites from the 

 source of inoculation and those from the inoculated person ; 

 whereas in two cases the inoculated person exhibited other 

 forms than those from the source of inoculation. The two 

 cases, however, that appear to support the view of poly- 

 morphism are, on more careful scrutiny, as Mannaberg 

 shows, not entirely free from criticism, so that the results 

 of the sixteen experiments render it highly probable that 

 the individual varieties of parasites represent distinct spe- 

 cies, which do not undergo a transformation into other 

 varieties. From the experiments, the conclusion is to be 

 drawn further that an unmistakable relation exists between 

 the type of fever and the species of parasites. 



Classification of the Malarial Parasites. The funda- 

 mental types of intermittent fever are the quotidian, the 

 tertian, and the quartan. In addition there occur fre- 

 quently irregular types, which pursue their course in part 

 continuously, in part with distinct remissions, or with 

 attacks following one immediately upon another. Of the 

 quotidian variety two forms have long been distinguished 

 namely, the double tertian and the triple quartan. The 

 different types are dependent upon different forms of para- 

 sites. The following are among those best known : 



i. The Quartan Parasite. The juvenile form of the 

 quartan parasite is an unpigmented body, with slow, ame- 

 boid movement, visible as a small, bright spot within the 

 infected blood-corpuscle. It grows but little during the 

 first twelve or twenty -four hours. Then pigment appears 

 in the outer layer in the form of coarse granules and rods ; 

 this is nonmotile. With increasing pigmentation the para- 



