i8 4 AIDS TO BACTERIOLOGY 



movements slacken. Ten to twenty segments develop, 

 which form round a central clump of pigment, like a 

 rosette, the blood-corpuscle breaks down, and the seg- 

 ments, which have now become spherical, are liberated. 

 Some enter red blood-discs and repeat the cycle (the human 

 phase, endogenous or asexual cycle), the bodies in the 

 corpuscles being known as amcebulse or myzopods, and 

 the liberated spheres as sporocytes or merozoites. The 

 liberation of the latter is coincident with the appearance 

 of a paroxysm. 



Varieties of the Malarial Parasite. Varieties of the 

 parasite supposed to be biologically distinct organisms 

 are associated with respective types of fever, which are 

 distinguishable clinically. 



(a) Quartan. This is a benign variety, and depends on 

 a parasite (Hcemamceba malarias) which takes seventy- 

 two hours to pass through its cycle of development. The 

 parasite is feebly amoeboid at first. The pigment is 

 abundant and coarse-grained, and the symmetrical rosette 

 that forms next produces six to twelve merozoites. The 

 red corpuscles invaded by the parasite do not become 

 decolorised or markedly enlarged. 



(b) Tertian. The cycle of development of this parasite 

 (H. vivax) takes forty-eight hours for completion. The 

 organisms within the corpuscles show much greater move- 

 ment than in the quartan type. The pigment granules 

 are fine, and show much movement. The sporulating 

 body consists of fifteen to twenty segments, which form 

 a mulberry mass. The corpuscles are frequently decolor- 

 ised and hypertrophied. 



(c) Malignant Tertian. This form (Hwmomenas prce- 

 cox) requires about forty-eight hours for development. 

 The organism is relatively minute, and is very actively 

 amoeboid when young, the parasite assuming a ' signet- 

 ring ' form after a time. Its more advanced or sporula- 

 ting stage is completed in the bloodvessels of the deeper 

 viscera. 



(d) Malignant Quotidian. The cycle of development 

 of this variety takes twenty-four hours. The parasite is 

 always small, even in the adult state, and frequently 

 assumes the ' ring ' form in the corpuscle. The spores 

 are generally formed by irregular segmentation. 



There is some disagreement as to the existence of 



