PARASITES IN MALARIAL FEVER 17 



examine with a low power under the microscope in order to 

 see if the leucocytes are well stained, and the nuclei a rich 

 purple, before proceeding to the next step, i.e., clearing. 



(3) Clearing. The mixture of the water and pre- 

 cipitated stain should be flushed off with distilled water. 

 A drop of distilled water should be left on the films, 

 which should be examined under the microscope. The 

 red corpuscles should not be blue, and water can be left 

 on until these appear red. This takes half a minute or 

 more. The water can now be poured off and the film 

 stood on its edge and allowed to dry. It may be blotted, 

 but fibres from blotting paper are so often mistaken for 

 spirochaetae or filariae that this is not recommended. 



Parasites of Benign Tertian and Quartan, Plasmodium 

 vivax and Plasmodium malarice. The living parasites in 

 their earliest stage are colourless bodies in the interior 

 of the red corpuscles. They can be distinguished from 

 vacuoles or rifts in the red corpuscles by the less sharply 

 defined edge and by a slight opalescence, so that they 

 do not appear quite so translucent. Amoeboid movement 

 can frequently be seen, and this is often active though 

 the pseudopodia at this stage are small. The quivering, 

 oscillatory movement of the haemoglobin forming the 

 edge of a vacuole must not be mistaken for amoeboid 

 movement. 



The parasites may be called amcebulae ; in the fresh 

 blood the parasites in this early stage have not obviously 

 altered the red corpuscle which contains them. Some 

 enlargement of the corpuscle may be seen in an infection 

 with the parasite of benign tertian malaria. 



There is, however, already a change, as the red cor- 

 puscles infected with benign tertian parasites do not 

 crenate as readily as the uninfected corpuscles. Some- 

 times when all the other red corpuscles in a field are 

 crenated, those containing the young forms are not 

 crenated. On the contrary, in a subtertian infection, 

 the corpuscles containing parasites crenate more readily ; 

 sometimes the only crenated corpuscle to be seen will be 



