THE MICROSCOPE IN MEDICINE AND SANITATION, m 



even smear. After drying in the air this is ready for 

 staining. 



One of the most satisfactory differential blood- stains 

 is Wright's modification of Leishman's method, described 

 in the Journal oj Medical Research for January, 1902 

 (volume VII, p. 138). The somewhat complicated pro- 

 cedure for making this stain and some discussion of 

 the philosophy of its action must be sought in the original 

 paper; but the student will find its application easy. 

 The dried film is covered with the solution of the dye in 

 methyl alcohol for one minute and water is added, drop 

 by drop, until the mixture becomes semi-translucent 

 and a yellowish metallic scum forms on the surface. 

 This mixture is allowed to stand on the preparation 

 for two or three minutes and then washed off in distilled 

 water till the film has a yellowish or pinkish tint in its 

 thinner portions. 



The slides thus stained, dried, and mounted in balsam 

 should show the various types of blood-cells beautifully 

 differentiated. The red corpuscles, or erythrocytes, are 

 orange or pink in color and about 7.5 /x in diameter. 

 The white cells may be divided into three classes accord- 

 ing to the relation which their nuclei and granules bear 

 to the constituents of the stain. The eosinophils or 

 oxyphiles are cells containing matter which takes such 

 acid stains as eosin. Stained with the Wright stain, these 

 appear faintly blue with a dark lilac-colored nucleus 

 and numerous large reddish granules. They are double 

 the size of the erythrocytes. The basophiles are cells 

 which take basic stains and are of two varieties. Small 



