1114 PATHOGENIC PROTOZOA 



into granules and threads, shows no real tendency to segment or 

 disperse, but remains a compact mass. 



The quartan parasite, when stained with Wright's or a similar 

 preparation, shows quite regular and symmetrical segmentation, 

 usually into eight merozoites. The distinction between schizont and 

 sporont and between male and female gametocytes may be made 

 on the same grounds as in tertian. 



In aestivo-autumnal fever the chromatin dot in the young ring 

 is often doubled, or even trebled, and in general is large and stains 

 brilliantly. The adult and half-grown gametes may be differentiated 

 into male and female by the criteria already given. 



The Examination of Fresh Blood. Directions have already been 

 given (Chap. LIX) for making wet preparations and if, by ringing 

 the cover-glass with vaseline, drying be prevented, the preparations 

 will keep and may be studied for hours. In tertian fever the young 

 ring forms are at first difficult to detect, unless the amount of light 

 going through the microscope be cut down to the minimum. As the 

 parasite grows older, an increasing number of hemozoin granules 

 appear, and since they are in constant motion the parasite is readily 

 detected. Its cytoplasm is delicate, and with very young parasites 

 is difficult to distinguish from the red cell itself; older parasites, 

 however, develop pseudopods, which are constantly projected and 

 retracted, and the entire organism shows active movements, render- 

 ing it easy to see. The pigment continues to increase, and in the 

 gametes is abundant and in constant motion ; the gametes, however, 

 fail to show any ameboid changes, and the protoplasm is stiff and 

 rigid with a regular, unbroken margin. At times a clear refractile 

 spot is seen, which is the nucleus. The infected erythrocyte is pale 

 and swollen. Even in unstained preparations the sexes may be 

 distinguished; the microgametocyte is about the size of a red cell, 

 the cytoplasm is hyalin, and after the preparation has been made 

 ten to twenty minutes the flagella, or microgametes, may be seen 

 thrashing about in the parasite. After repeated attempts four to 

 eight microgametes rupture the cell and emerge. The macrogamete 

 is larger than a red cell and is finely granular and no exflagellatioii 

 of microgametes occurs. 



In quartan malaria the differences already described in stained 

 blood may be easily followed. 



In aestivo-autumnal fever the diagnosis with fresh blood is much 

 more difficult in new infections because of the relative scarcity of 



