30 



BODIES THAT MAY BE MISTAKEN FOR PARASITES 



1. Platelets. A single platelet lying on a red 

 cell is often taken for a parasite. It is often quite 

 round, but it is granular in appearance, and stains 

 uniformly red or blotchy purple. There is no distinct 

 separation into red nucleus, white vacuole and blue 

 protoplasm. 



Platelets lying free may show a great variety of 

 shape, round, oval, sausage-shaped, in masses from 

 the size of one-fifth to three or four times that of a 

 red cell. They often, too, appear to have a clear 

 outline, but the resemblance to a parasite is only 

 superficial. There are no distinct areas, and, further, 

 free parasites are practically never seen. Again, 

 crescentic masses of platelets are often taken for 

 crescents ; but, again, there is no red chromatin and 

 separate blue protoplasm, and no pigment. 



2. Stained Vacuoles. Artefacts of this kind 

 generally occur in almost every cell in some portion 

 of the field while quite absent in others. This is, of 

 course, not the case with parasites. They are granular 

 and much like a platelet, but lack the ' red, white and 

 blue ' of a parasite. 



3. Leucocytes. Are not uncommonly mistaken 

 for large forms of parasites, e.g., gametes, but if it is 

 remembered that the greatest amount of chromatin 

 in a gamete is always quite small, while, comparatively, 

 the nucleus of a leucocyte is immense, this mistake 

 cannot be made. 



4. Basophilia of Red Cell. Occasionally mis- 

 taken for a red cell shewing SchiifTner's dots, containing 

 a simple tertian -.parasite. Closer observation shews 

 that the punctate cell contains no parasite. 



5. Normoblasts. The red cell contains a nucleus 



