cytoplasm, one or two minute round dots of intensely black material optically indistinguishable from hæmozoin. I am not aware that this appearance has been described hitherto, but multiplied observation has convinced me of the accuracy of my statement. The discovery, therefore, of what looks like a speck of intensely black pigment in the lymphocytes must not be regarded as evidence of malarial infection.
Diagnosis of vacuoles.—The beginner may have a difficulty in determining whether certain appearances in the corpuscles are vacuoles, or whether they are parasites. The following hints may help him to
Fig. 17.—Vacuolated and crenated blood-corpuscles. (After Laveran and Blanchard.)
a correct decision: Vacuoles (Fig. 17, a, b, c, d, e, f, h, i, j, k, l) are well defined, clear, and have sharp edges; they may change form slightly, but they have no true amœboid movement, carry no pigment, and, of course, do not stain. Intracorpuscular malaria parasites, on the contrary, are dim and, as a rule, ill defined; they have soft, shaded-off edges; possess amœboid movements; when large they carry hæmozoin grains; and, of course, they take the appropriate stains. It is hardly necessary to indicate the points of diagnosis from leucocytes, or from cupped, folded, or crenated (Fig. 17, c, f, g, i, j, k, l) corpuscles.
Moribund and fragmented parasites.—Moribund—it may be fragmented—free parasites (Fig. 18) are
