STAINING BLOOD-FILMS 205 



After the use of this stain nuclei are stained blue, red corpuscles 

 red, eosinophile granules red, and basophile granules violet. The 

 descriptions of the leucocytes and abnormal red forms, which are 

 appended, are all based on the appearances seen in films stained 

 by this method, from which also Plates VII. and VIII. were drawn. 



Jenner's stain is suitable for a study of the parasite of malaria, 

 which it stains blue. It may be used for the detection of bacteria. 



Leishman's stain is similar in some respects to Jenner's, and is 

 used as follows : The film is flooded with the stain, which is allowed 

 to act for two minutes ; two or three drops of distilled water are 

 then added, and the process allowed to continue for two or three 

 minutes longer. It is then washed, dried, and mounted as above. 

 The colours of films stained by this method differ from those in 

 which Jenner has been used, the main point being that the nucleus 

 of the leucocytes is a fine purplish red ; the leucocytes, however, 

 can be easily recognised from the coloured plates. 



Leishman's method is the best for working with malaria and all 

 parasitic protozoa, the nuclei of which are stained a bright red. 

 For ordinary blood-work I personally prefer Jenner (perhaps 

 because I am more used to it), and the practitioner is recommended 

 to choose one process and stick to it. If he is likely to need it for 

 malaria or other parasites, Leishman's stain should be used. 



3. Eosin and methylene blue used separately. 



In this method the films are to be stained with the eosin first, 

 and then with the methylene blue. Its successful application 

 requires a certain amount of practice. 



The eosin used must be in watery solution, and the exact 

 strength does not matter : 4 per cent, is a convenient strength to 

 use. Most specimens of red ink (slightly diluted) will do quite 

 well. The films are to be stained in this solution for three or 

 four minutes ; no harm will result if they are left in much longer. 

 They are then washed and immersed in a saturated watery 

 solution of methylene blue. This is the difficult part of the pro- 

 cess, for no general rule can be given as to the length of time for 

 which this stain must be applied ; it may be ten seconds, or it 

 may be two or three minutes. The only safe way is to stain the 



several months after being opened, if kept well corked), the method described 

 will always succeed if well-spread films are used. This is essential. But even 

 with bad films (and very bad ones are sent me at times) the results are always 

 suificiently good to allow a differential leucocyte count to be made. 



