DIFFERENTIAL COUNTING OF LEUCOCYTES 21 



Wash in water. 



Stain one-half to one minute with a five-tenths per cent, aqueous 

 solution of methylene blue (Griibler's BX). 



Wash in water, blot. 



The resulting picture is much like that afforded by the Ro- 

 manowsky stains excepting that the granules of leucocytes and 

 myelocytes are much more prominent. The granules of polymor- 

 phonuclears, eosinophiles and myelocytes are purplish red, those of 

 mast cells a deep purple. Red corpuscles are greenish yellow to 

 pink, platelets blue, nuclei of all cells blue and cytoplasm light 

 blue. The best results are obtained with freshly made smears as 

 the reacting substance begins to disappear after ten days to two 

 weeks. 



DIFFERENTIAL COUNTING OF LEUCOCYTES 



In making a differential count ordinarily at least 500 leucocytes 

 should be examined; for critical work twice that number should 

 be counted. For recording the results it will be found convenient 

 to rule a sheet of paper as follows, giving a column in which to 

 record each variety of leucocyte and a blank space for recording 

 myelocytes, degenerated leucocytes, abnormal red corpuscles, et 

 cetera : 



