520 



A MANUAL OF BACTERIOLOGY 



the Gnats and Mosquitoes ; Daniels, Laboratory Studies in Tropical 

 Medicine, ed. 3, 1908.) 



There are probably at least three species of malaria 

 parasite l occurring in the various types of malarial fever 

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

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

 are the differential characters between them : 



(1) Benign quartan fever (Fig. 62). The quartan parasite 



FIG. 62. The quartan parasite : a, 6, c, d, amoebulse ; e, 

 sporocyte ; /, free spores ; g, female gametocyte with so- 

 called polar body ; h, male gametocyte. (After Rees.) 



(Plasmodium malarice) completes its asexual life- cycle 

 in seventy- two hours ; 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 " quar- 

 tan." It commences as a small amcebula, which is feebly 

 motile. It enlarges, becomes pigmented, and motility 

 ceases, the pigment-granules being numerous and coarse. 

 The parasite 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 

 of six to twelve spores (/). The quartan parasite does not 



1 Hewlett, Trans. XlVth Internal. Congress of Hygiene, vol. ii. 1908, 

 p. 141, 



