136 MALARIA 



life-cycle varies in the different species. The account 

 given here applies in the main to them all. ■ 



The organism which Laveran saw living in the 

 blood-corpuscles of his malarious patient was a minute 

 cell of irregular shape whose nucleus can be demon- 

 strated by the use of appropriate reagents. The cell 

 constantly but slowly changes its outline, pushing 

 out and withdrawing blunt rounded processes ; in 

 fact, the cell resembles the lobate forms of one of the 

 simplest microscopic animals we know, the Amoeba 

 (Fig. i). The movements and change of shape con- 

 sequent on them are termed amoeboid, and the 

 organism in this stage is known as an amoebula. 

 These amoebulae whilst in the blood-cell grow rapidly, 

 and in some way they collect the haemoglobin, or 

 colouring matter of the red corpuscle, within their 

 own bodies, and convert it into a number of dark 

 brown or black pigment granules, which crowd around 

 the nucleus of the parasite. This pigment, the so- 

 called malarial pigment or melanin, had been recog- 

 nized by Virchow and others about the middle of the 

 nineteenth century as a characteristic product in the 

 blood of malarial patients. The amoebulae continue 

 to grow rapidly, at the expense of their cell-host, 

 until, after a definite period, which varies from one to 

 several days, they become mature, and by this time 

 they have completely filled up the red corpuscle, 

 whose scanty remains form a tight skin round the 

 fully-grown parasite (Fig. i, i-8). When mature, one 

 of two things happens — either they become (i) game- 

 tocytes, whose meaning and fate we will consider 

 later, or they become (2) sporocytes. In the latter 

 case the nucleus of the amosbula breaks up into a 

 number of small nuclei, and each surrounds itself by 

 a small mass of protoplasm and forms a spore 

 (Fig. I, S-8). The result of this process of division 

 may be roughly realized if we imagine an orange with 



