520 APPENDIX C. 



be distinguished (Figs. 161, 162). The former appears as a small 

 rounded body which usually remains unstained, but contains a minute 

 mass of chromatin which stains a deep red with the Romanowsky 

 method ; the peripheral protoplasm is coloured fairly deeply with methy- 

 lene-blue. The spores show little or no amoeboid movement ; at first 

 free in the plasma, they soon attack the red corpuscles, where they be- 

 come the intra-corptiscular amoebulae. If the blood, say in a mild ter- 

 tian case, be examined in the early stages of pyrexia, one often finds at 

 the same time sporulating forms, free spores, and the young amoebulae 

 within the red corpuscles. 



2. Infra-corpuscular Bodies or Am&bulce. These include the para- 

 sites which have attacked the red corpuscles ; they are at first situated 

 on the surface of the latter, but afterwards 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, of about the same size as the spores. As 

 seen in fresh blood, they exhibit more or less active amoeboid move- 

 ment, showing marked variations in shape. The amount and character 

 of the amoeboid 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. 158, 159). The pigment may be scattered through their sub- 

 stance, or concentrated at one or more points, and often shows vibratory 

 or oscillating movements. This pigment is no doubt elaborated from 

 the haemoglobin of the red corpuscles, the parasite growing at the ex- 

 pense of the latter. The red corpuscles thus invaded may remain unal- 

 tered in appearance (quartan fever), may become swollen and pale 

 (tertian fever), or somewhat shrivelled and of darker tint (malignant 

 fever). In stained specimens a nucleus may be seen in the parasite as 

 a pale spot containing chromatin which may be arranged as a single 

 concentrated mass or as several separated granules, the chromatin being 

 coloured a deep red by the Romanowsky method. The protoplasm of 

 the parasite, which is coloured of varying depth of tint with methylene- 

 blue, shows great variation in configuration (Fig. 159). The young 

 parasites not unfrequently present a " ring-form," a portion of the red 

 corpuscle being thus enclosed by the parasite. These ring-forms are 

 met with in all the varieties of the parasite, but they are especially com- 

 mon in the case of the malignant parasite, where they are of smaller 

 size and of more symmetrical form than in the others, representing a 

 quiescent stage (Fig. 163) ; the pigment is usually collected in a small 

 clump at one side. 



Within the red corpuscles the parasites gradually increase in size till 

 the full adult form is reached (Fig. 160). In the latter stage the para- 



