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40 often a source of confusion to the beginner. Their nature is frequently misunderstood; they are sometimes erroneously termed "sterile bodies," an expression at one time frequently applied to the crescent-derived spheres (gametocytes). They are, in fact, mechanically-freed parasites expressed from blood corpuscles by the compression to which the blood is subjected between slip and cover-glass. The longer blood is on the slide—particularly if evaporation be not prevented by vaseline-ringing of the cover-glass—the more closely will the cover-glass approximate to the slip, the greater will be the pressure on, and consequent thinning and spreading out of, blood corpuscles and parasites, and the greater the liability to damage of these very delicate



bodies. Frequently the artificially-freed parasites are broken into small fragments. The entire, as well as the fragmented parasites, on becoming free in the liquor sanguinis, tend to assume a spherical or disc-like form; at the same time the protoplasm of which they are composed seems to become diffluent, and the hæmozoin is resolved into a number of minute dust-like particles possessing active, brownian movement. Some of the spherical or disc-shaped bodies with dancing hæmozoin particles are really crescent-derived spheres or other forms of gametes. These are parasites which have escaped from corpuscles in a normal way, but which have become arrested in their evolution in consequence of the abnormal conditions in which they are placed in vitro; others are the remains of flagellated bodies, the microgamete filaments having broken away.