644 A MANUAL OF BACTERIOLOGY 



There are probably at least three species of malaria 

 parasite 1 occurring in the various types of malarial fever 

 in man, though some authorities (e.g. Laveran) regard 

 the forms as varieties of a single species, and the following 

 are the differential characters between them : 



(1) Benign quartan fever (Fig. 61). This is a relatively 

 uncommon form of malaria, being frequent only in certain 

 districts. The quartan parasite (Plasmodium malarice) 

 completes its asexual life-cycle in seventy -two hours ; 



FIG. 61. The quartan parasite : a, b, c, d, amoebulse ; e, sporocyte ; 

 /, free spores ; g, female gametocyte with so-called polar body ; 

 />, male gametocyte. (After Rees.) 



there are two complete days without an attack, and 

 reckoning the day of the previous attack, an attack occurs 

 every fourth day, hence the name " quartan." It com- 

 mences as a small amcebula, which is feebly motile. It 

 enlarges, becomes pigmented, and motility ceases, the 

 pigment-granules being numerous and coarse. The para- 

 site finally occupies nearly the whole of the corpuscle, 

 which, however, is but little altered (a-d). 



Towards the end of the apyrexial period the pigment 

 collects in the centre, and segmentation takes place with 

 the formation of a symmetrical rosette (e), and afterwards 



1 Hewlett, Trans. XlVth Internat. Congress of Hygiene, vol. ii, 1908, p. 141. 



