the sharpness or obtuseness of the horns, occur; but, on the whole, the crescents are very uniform in appearance. Very rarely twin or double crescents—that is, two crescents in one corpuscle—are encountered (Fig. 6).
Fig. 6.—Malaria parasite:
twin crescents.
Crescents differ in appearance according to their age; in some the hæmozoin granules are scattered throughout the parasite, in others they are concentrated, and in a third class the protoplasm shows vacuolation and other signs of degeneration. The first, it is believed, are young and immature, the second mature, and the third effete parasites. In the first, the hæmozoin rods sometimes exhibit slight translation as well as vibratory movements; in the two latter the hæmozoin is quiescent. The first, or younger, type of crescent stains uniformly; but in the second type the staining, in many instances, is markedly bipolar, a clear, unstained area occupying the middle of each horn, whilst a zone of stained protoplasm forms the periphery, and a bridge of stained material divides the two horns at the centre of the crescent. By dissolving the hæmozoin particles at the centre of the crescent with weak solution of ammonia, and subsequently staining, a nucleolus, sometimes double, can be demonstrated.
As will be shown in the sequel, these crescent bodies and the large intracorpuscular forms just alluded to are sexual in their functions. As regards the crescents, there are certain differences in the appearance of the protoplasm, in the arrangement of the pigment, and in the characters of the nucleus as revealed by staining, which are distinctive of the male and female crescents respectively. In one type of crescent the protoplasm is hyaline and the hæmozoin somewhat loosely arranged. In another type the protoplasm is faintly granular and the hæmozoin more concentrated, being arranged as a well-defined ring about the centre of the parasite.
