20 TROPICAL MEDICINE AND HYGIENE 



contained in the red corpuscle is exhausted, and the 

 further changes are those leading to multiplication and 

 reproduction. This may be asexual or sexual. In the 

 former, the most frequently seen, the first changes that 

 are observed in the fresh blood are that the pigment 

 aggregates in a clump in the interior of the parasite. 

 This clump is at first loose, so that the individual grains 

 of pigment are easily distinguished, but these soon become 

 so closely packed that it appears almost as a solid block 

 of pigment. By this time traces of the division in the 

 parasite will be visible. At first these are only seen with 

 difficulty, but soon become more marked, so that the 

 whole of the protoplasm, except a minute residuum round 

 the pigment, is divided into a series of oval unpigmented 

 masses, five to ten in number in quartan and eighteen to 

 twenty-four in benign tertian. Very rarely a larger or 

 smaller number of those ovoid masses spores may be 

 found in these sporulating parasites. The red corpuscles 

 containing the parasites soon burst, and the spores, pig- 

 ment, residual protoplasm, and any fluid or solid residue 

 of the red corpuscle, probably including toxic substances, 

 are set free in the blood plasma. The pigment is taken 

 up by leucocytes, usually by the large mononuclear 

 leucocytes. 



The spores do not long remain free in the peripheral 

 blood ; they rapidly try to enter other red corpuscles. 

 Many must fail to do so and be rapidly destroyed, as 

 the number of young parasites found is far less than 

 it would be if all the spores were able to enter red 

 corpuscles ; nor does the rapid increase in the number 

 of parasites occur with the successive sporulations as 

 might be expected. 



This process of reproduction is commonly termed 

 sporulation, but is more correctly termed schizogony. 

 The sporulating parasites would then be known as 

 schizonts and the spores as merozoites. 



Sexual Phase. Sporogony. The parasites destined for 

 a sexual life in benign tertian and quartan malaria are 



