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). 



