PAEASITE OF PERNICIOUS MALARIA 191 



of fresh blood, unstained, placed upon a slide and under cover-glass. It is the 

 method least employed because it requires greater technical skill ; it permits, 

 however, all the details to be seen, as Schaudinn has shown. Among other 

 notable achievements he succeeded with this method in following clearly the 

 penetration of the sporozoit into the blood-cell. The second method consists 

 in staining the blood which has been spread in a very thin layer upon a micro- 

 scope-slide. There are various methods of staining which all have as a basis 

 more or less the same color substances. That most in actual use, because it is 

 the simplest and the one which enables all the details of the parasite to be dis- 

 tinguished, is the process of Giemsa. 



Plasmodium malarice (the organism of quartan malaria). — ^When one ex- 

 amines with the microscope a slide with live parasites of quartan fever one sees 

 that their movements are much weaker than those of Plasmodium vivax. The 

 black pigment-granules appear early; the parasitized red blood-cell shrinks a 

 little, and in stained preparations this can be seen readily. The quartan parasite 

 sometimes also produces a heavier coloration ; however it does not possess granu- 

 lations like those of Schiiffner (seen in stained preparations as small red dots) 

 in Plasmodium vivax, or of Maurer (a very few dots) in P. falciparum. Schi- 

 zogony takes place only in the peripheral circulation. The parasite divides into 

 from 8 to 14 merozoits arranged with great regularity, hence this phase is some- 

 times called the " rosette," " daisy," or " marguerite " form. The evolution 

 takes longer than in any other plasmodium, 72 hours being consumed from one 

 schizogony to the next. There is a characteristic appearance which this parasite 

 assumes during growth, that of a more or less broad band across the corpuscle 

 which is by many called the cequatorial hand. The gametes are round, not only 

 when inside of the corpuscle, but also when free in the blood-plasm. 



Plasmodium falciparum. — The disease caused by this parasite goes under 

 several names : quotidian^ malignant tertian, atypical, irregular, cestivo-autum- 

 nal, pernicious, or tropical fever. The Germans follow Koch and use the term 

 " tropical fever " but this expression is not in accord with the geographic dis- 

 tribution of the parasite. The differentiation of this parasite is based more on 

 clinical data than on the structure and biology of the organism. When alive the 

 schizont is very active. Schizogony takes place in less regular periods than in 

 the other parasites, fluctuating between 24 and 48 hours. Doflein states that 

 there may be a prolonged period of 72 hours. Also the number of merozoits is 

 variable and may range from 4 to 30, although commonly between 6 and 14. 

 The division always occurs in the internal organs ; in acute cases it can, however, 

 also be found in the periphery. In this parasite there is commonly formed a pre- 

 cocious division in the young forms, a fact which explains the rapid progress 

 which pernicious attacks make. Besides the habitual cycle, then, the parasite 

 can subdivide before it has completed it. It is quite common to find blood-cells 

 containing more than two schizonts ; there have already been found as many as 

 6 or 7 in a single corpuscle. A peculiarity of this parasite is its retreat to the 

 internal organs after 30-36 hours; after having divided the parasites reappear 

 in the periphery, generally two or three hours after this process. To this phe- 



