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How to find
the parasite.
On searching each corpuscle he will presently come across one
in which fine black dots of pigment are seen. On focussing carefully
he will find that these dots are contained in a transparent mass
of pale protoplasm which is undergoing amoeboid movement inside
the corpuscle. After a short time the movements will become less
marked, and the outline of the body will become more distinct. Careful
watching will convince the observer that he is looking at a living
parasite. Once having found a parasite, the beginner will know what sort
of body to look for, and will easily be able to educate himself to pick out
the smaller forms.
Stained films.
Stained films can be examined at once with the one-twelfth inch objective,
and the illumination should be as brilliant as possible. The drop of cedar
wood oil should be placed on one of the side edges of the film, and different
fields along this edge should be searched until the examination is ended. By
the method of staining which has been described here the red blood corpuscles
are stained pink and the blood platelets and the nuclei of the leucocytes a
deep ruby-red.
Leucocytes.
Polynuclear leucocytes will be recognised by their large irregular
nucleus ; their body protoplasm is unstained and contains fine red
granules.
Large mononuclear leucocytes have generally a large oval or horse-shoe
shaped nucleus and faintly blue stained body protoplasm which is free from
granules. They may contain grains of intensely brown or black malarial
pigment (melanin) which should be carefully looked for as they are a sign of
recent infection.
Lymphocytes have a round, ruby-red nucleus surrounded by a thin rim
of blue stained protoplasm.
Eosinophile leucocytes have generally two pear-shaped nuclei joined
together at the top, and numerous large, round, red granules scattered
through the cell, which make them very easily recognisable.
Blood
platel ets.
The blood platelets are deep ruby-red, and will generally be found in
groups looking something like bunches of grapes. Many beginners mistake
them for the "spores" of malaria parasites.
Malaria parasites are very easy to detect in the red blood corpuscles by