278 APPLIED BACTERIOLOGY 



crescent there is always a mass of motionless pigment 

 granules about its centre. During the change of form 

 described this mass of pigment still remains passive and 

 central. The sphere once formed, however, a change 

 occurs in this respect, the pigment granules beginning to 

 move, at first slowly, but presently more actively, dancing 

 about in the most energetic manner in the centre of the 

 parasite. By-and-by, their agitation increasing, they burst 

 through what Dr. Manson takes to be the delicate membrane 

 hitherto enclosing them. The pigment now becomes 

 diffused throughout the entire mass of the sphere, and 

 continues to indulge in violent boiling-like movement 

 (Fig. 22 — 11). At the same time the sphere itself becomes 

 agitated — excited, as it were — changes form, writhes, is 

 jerked violently about by some unseen force, and then 

 suddenly flagella are projected from its circumference 

 (Fig. 22 — 12), just as already described in the case of the 

 free spheres of the quartan and the benign tertian parasite. 

 That these ellipsoidal and spherical forms do not exist as 

 such in the circulating blood may be proved, as in the case 

 of the tertian and quartan plasmodium, by fixing the blood 

 immediately on its removal from the body ; on such slides 

 — even although wet slides prepared simultaneously may 

 exhibit crescents, ellipsoids, and spheres — we never find 

 the two latter forms, but only crescents, and, of course, 

 should fever be present or imminent, the usual intra- 

 corpuscular forms of the plasmodium. This transformation 

 of the crescent into the flagellate body is a very striking 

 phenomenon, and must be referred to one of two things. 

 Either it is a degenerative change in a dying or dead para- 

 site, or it is a vital evolutionary change — a normal step in 

 the life of the parasite. Dr. Manson 's conviction is that it 

 is the latter, and that the flagellated body is the first phase 

 of the extra-corporeal plasmodium. 



