128 LABORATORY BACTERIOLOGY 



parasites are in use, but the following (Nocht-Romanowsky) 

 gives the most uniform, satisfactory results. 



Preparation of stain, i. To one ounce of polychrome 

 methylene blue (Griibler) add a 3% solution of acetic acid 

 (U.S.P., 33%) drop by drop until it no longer turns red 

 litmus paper blue above the zone coming into immediate 

 contact with the dye. It usually requires about five drops. 



2. Make a saturated (i %) watery solution of methylene blue, 

 preferably Ehrlich's (Grubler) or Koch's, dissolving the dye 

 by gentle heat. This solution improves with age, and should 

 be at least one week old. 



3. Make a i% watery solution of Grtibler's watery eosin. 

 The mixture is prepared as follows : 



To 10 cc. of water add 4 drops of the eosin solution, 6 

 drops of neutralized polychrome blue, and 2 drops of i % 

 methylene blue, mixing well. 



Preparation of films for staining malaria organisms in the 

 blood. Clean the finger or ear lobe with alcohol, and prick 

 with a sterile surgical needle or lance so as actually to incise 

 the capillaries. The blood should not be squeezed out, but 

 should flow freely. Wipe away the first two or three drops. 

 Apply the edge of one end of a glass slide to a small drop 

 of blood and place this edge on the surface of another slide 

 resting on a firm surface. As soon as the drop of blood has 

 spread along the line of contact, holding the slide at an angle 

 of about 30, draw it gently along the surface of the receiving 

 slide, spreading the blood in a thin film. Allow the films to 

 dry in the air before fixing. 



Fixing the blood films, i. By heat, (a) Open flame. Pass 

 the slide, specimen side up, slowly through the flame of a 

 Bunsen burner until it is decidedly too hot for the hand to 

 bear. At this temperature, which probably varies from 110 

 to 150 C, fixation is complete in from i to 2 minutes. Over- 

 heated slides can usually be seen to change color in the flame, 

 after which the red cells stain yellowish with eosin. A little 



