152 MALARIA 



explains the occasional distinct projection of the parasites at 



the periphery or edge of the corpuscles (Fig. 44) ; and it accounts 



for the ease with which the parasites may be distorted in making 



blood smears. Another argument in favor of 



Qthis theory as opposed to the intracorpuscular 

 theory is that the haemoglobin in the corpuscles 

 is believed to be in a more or less solid state, 

 ^ and would therefore make it difficult for the 

 parasites, if situated inside, to indulge in such 



O active movements as they do. The majority 

 of protozoologists, however, have not accepted 

 B Mrs. Johnson's conclusions. 

 As the parasite develops there is a distinct 

 corpuscles showin d tendency ^ or ^ ne affected corpuscles to clump 

 malaria parasites together, thus clogging the tiny capillaries which 



ar are ^ ar S e enough to allow the passage of only a 



sites resting one single corpuscle at a time. In this way the 



?ai v f i. th 1 the ^' capillaries of such organs as brain, spleen, bone 



(Sketches from mi- 



crophotographs by marrow and others may be obstructed to a 



fatal de S ree - Three-fourths of the life cycle of 

 the parasites is usually passed in the plugged 

 capillaries so that only during one-fourth of their cycle can they 

 be found readily in the circulating blood. 



After about forty hours the nucleus of the parasite divides into 

 a variable number of fragments, usually from ten or 15 to as 

 many as 32, i.e., under favorable conditions it may split five 

 times, into two, four, eight, 16, and 32 parts. The rest of the 

 body divides itself into portions, one surrounding each fragment 

 of the nucleus, thus forming a little heap of " spores " (Fig. 43E) 

 ready to burst apart and leave the corpuscle on which the 

 parent parasite had been feeding. In the center of the heap 

 can be found a little mass of coal-black pigment granules, the 

 waste products resulting from the digestion of the oxygen- 

 carrying red substance of the blood, haemoglobin. When the 

 parent parasite bursts the young parasites formed by this rapid 

 process of multiplication are set free (Fig. 43F) in the blood where 

 each enters a new corpuscle and repeats the process of growth 

 and reproduction. The pigment and other waste products 

 which are left behind when the parasite multiplies are released 

 into the blood stream where they are carried to all parts of the 



