25 
there should be a central transparent area shewing no 
sign of a granular appearance, and even looking quite 
free from blood. If this appearance is present, the film 
is probably a good one. If the centre of the film 
appears reddish or granular, it is useless to examine it 
(for young parasites), as the corpuscles will be massed 
together and the parasite not seen. N.B.—Under the 
microscope a good film should shew clear, even, circular 
discs, lying side by side and not overlapping each other 
(Fig. ii). 
