FORMS OF THE MALARIAL PARASITE. 517 



2. Epi- or Intra- corpuscular Bodies. These include 

 the parasites which have attacked the red corpuscles ; they 

 are at first situated on the surface of the latter but after- 

 wards penetrate their substance. They usually occur 

 singly in the red corpuscles, but sometimes two or more 

 may be present together. The youngest or smallest forms 

 appear as minute colourless specks, scarcely exceeding i //, 

 in diameter. As seen in fresh blood, they exhibit more 

 or less active amoeboid movement, showing marked varia- 

 tions in shape. The amount and character of the amoe- 

 boid movement varies somewhat in different types of fever. 

 As they increase in size, pigment appears in their interior 

 as minute dark brown or black specks, and gradually 

 becomes more abundant (Figs. 119, 120). The pigment 

 may be scattered through their substance, or concentrated 

 at one or more points, and often shows vibratory or 

 oscillating movements. This pigment is no doubt derived 

 from the haemoglobin of the red corpuscles, the parasites 

 growing at the expense of the latter. The red corpuscles 

 thus invaded may remain unaltered in appearance, may 

 become swollen and pale, or somewhat shrivelled and of 

 darker tint. In stained specimens a nucleus may be seen 

 in the parasite as a pale spot containing a minute and 

 deeply-stained nucleolus, the nucleus being more distinct 

 at some stages than at others. Sometimes, namely in the 

 quotidian and malignant fevers, the parasite passes into a 

 quiescent "ring form." The organisms in this condition 

 show a well-defined outer circular margin and a central 

 spot which is less sharply marked off, the pigment being 

 usually collected in a small clump at one side (Fig. 122). 

 These ring forms may again assume amoeboid movement. 



Within the red corpuscles the parasites gradually increase 

 in size till the full adult form is reached (Fig. 120). In 

 the latter stage the parasite loses its amoeboid movement 

 more or less completely, has a somewhat rounded form, 

 and contains a considerable amount of pigment. Some- 

 times, for example in the quotidian form, it only occupies 

 a fraction of the red corpuscle. The adult parasites may 



