SECTION TWO 



2. A drop of blood 2 to 3 mm. in diameter is placed on another 

 slide and brought in contact with the dried stain ; the two slides 

 are then manipulated hinge-like until all the stain has gone into 

 solution and the blood appears blue-black. Allow the slides to 

 come into contact to spread the drop ; then separate the slides and 

 allow the films to dry. 



3. Counterstain with Leishman or Wright by the standard 

 technique. 



Results : 



Reticulum of immature red cells is stained clear cut blue; 

 background, pale blue or pink. Blood platelets: pale blue or 

 lilac. 



Note: The counterstain may be omitted if it is desired only to 

 count the platelets. 



The number of red cells per cm. should be determined separ- 

 ately in a haemocytometer, and the ratio of platelets to red cells 

 computed from the stained preparation. 



For reticulum 



Stock solution: 



Brilliant Cresyl Blue .. .. 1-5 gm. 



Normal saline (0-85% NaCl) . . 100 ml. 



Technique: 



1. Mix a small quantity of the stock solution of the stain with 

 140 times its volume of normal saline solution. 



2. Mix the blood in a white-cell counting pipette in the propor- 

 tion of I volume blood to 20 vols, of the diluted staining solution. 

 Shake the mixture for five minutes in the pipette, and place in a 

 blood counting cell. 



3. The fresh preparations are sealed with petroleum jelly to 

 prevent drying, and are counted immediately. At least 1,000 

 should be counted for each test. 



Result: 



Reticulum only stained (blue). 



Reference: Robertson, O. H. (iQi?)- 



