CULTIVATION OF MALARIAL PARASITE 289 



schizont containing red cells disappear from the peripheral circulation so that the 

 further development is rarely observed in blood specimens. 



The infected cell is brassy in color and shrunken in shape it shows evidences 

 of degeneration. The gametes appear as crescent-shaped bodies, which are abso- 

 lutely characteristic of malignant tertian, the male gamete being more hyaline and 

 delicate while the female one is more granular and larger. 



In Romanowsky stained preparations we see, while the fever is sustained, small 

 hair-like rings, with geometrical outline, with frequently two chromatin dots in one 

 end of the ring and a single red cell often showing two or more of these young rings. 

 The rings are often seen as if plastered on the periphery of the red cells or as if having 

 destroyed a rounded section of the rim of the red cell. As the fever declines the 

 rings tend to disappear from the peripheral circulation. The infected red cells often 

 show polychromatophilia and distortion. 



In old aestivo-autumnal cases, or those with severe infection, we may see adult 

 rings and merocytes, which latter are smaller than those of benign tertian, show from 

 1 6 to 32 irregularly placed merozoits and a sharply clumped mass of pigment. 



The gametes are the striking crescent-shaped bodies and these show the distinc- 

 tions of blue staining for the female, with lighter gray-green staining and abundance 

 of chromatin for the male. The chromatin staining of crescents does not stand out 

 so well as that of the round form gametes of benign tertian and quartan. 



As regards differentiation of species and cycle the examination of 

 stained smears is more satif actory and definite, as well as less time con- 

 suming. Still, one obtains many points of differentiation in the fresh 

 preparation and should study such a preparation while carrying out the 

 staining of his dried smear. 



Central vacuolation of red cells is common in malarial anaemia and may be mis- 

 taken for nonpigmented parasites. 



Malarial rings are usually peripheral and do not vary in size as one focuses up and 

 down as do the central vacuoles. 



A very puzzling but well-recognized finding in cases treated with quinine or sal- 

 varsan is the so-called quinine affected parasite. Such parasites lack definiteness 

 of outline and show poor chromatin staining. The gametes do not seem to show 

 these effects from the drug. 



Cultivation. As to cultivation of malarial parasites. Bass takes from 10 to 20 

 c.c. of blood from the malarial patient's vein in a centrifuge tube which contains 

 Ho c.c. of 50% glucose solution. A glass rod, or a piece of tubing extending to 

 the bottom of the centrifuge tube is used to defibrinate the blood. After centri- 

 fugalizing there should be at least i inch of serum above the cell sediment. The 

 parasites develop in the upper cell layer, about > to Ko inch from the top. All of 

 the parasites contained in the deeper lying red cells die. To observe the develop- 

 ment, red cells from this upper Ko-inch portion are drawn up with a capillary bulb 

 pipette. 



Should the cultivation of more than one generation be desired, the leukocyte uppe 

 layer must be carefully pipetted off, as the leukocytes immediately destroy the 

 merozoites. Only the parasites within red cells escape phagocytosis. 



