384 CLINICAL BACTERIOLOGY. 



The presence of even a single undoubted malarial parasite 

 establishes the diagnosis with certainty. Should the result 

 be negative, it must be borne in mind that after the action 

 of quiriin the parasites at times can not be found in 

 the blood ; further, that they are sometimes wanting after 

 quite recent infection during the first days of the disease. 

 Negative results from a single observation are, therefore, not 

 conclusive, even when a large number of specimens have 

 been examined. Repeated examinations must be made, 

 preferably from three to ten hours in advance of the par- 

 oxysm, when the parasites have reached the height of their 

 development. 



In the determination of the variety of parasites, and 

 with regard to the prognosis, it is especially important to 

 decide whether crescents and their spindles or spheres are 

 present. The characteristics of these have been described. 

 The recognition of the species, as well as the decision 

 whether several generations of the parasite are present, 

 naturally demands continued observations, to be repeated 

 in the course of several hours. The differentiation of free 

 bodies moving about in the blood is attended with consider- 

 able difficulty, and opportunity is here afforded for confusion 

 from several sources. The parasitic nature of the bodies 

 contained within the red blood-corpuscles is, however, more 

 readily appreciated. The presence of pigment is here 

 especially of significance. Only the unpigmented juvenile 

 forms may occasion difficulty, as they may be readily mis- 

 taken in living preparations for vacuoles of the red blood- 

 corpuscles. The structure, which can not be overlooked, 

 especially in stained preparations (nucleus), is decisive in 

 this connection ; the vacuoles of the blood-discs are struc- 

 tureless. 



Explanation of the Symptoms of Malaria by the 

 Presence of the Parasites. The parasites of malaria are 

 present exclusively in the blood. Even in the viscera they 

 are found only within the capillaries. The melanemia of 

 malarial patients, which has long been known, is explained 

 by the conversion of the hemoglobin into melanin within 

 the parasites. The melanin is set free in the process of 

 sporulation, when it floats about in the plasma and is taken 

 up by the leukocytes. The infection of the blood-corpus- 

 cles by the parasites furnishes a direct explanation for the 

 anemia that arises in the course of malaria. The infected 



