MORPHOLOGY OF LEUCOCYTES AND RED CORPUSCLES 261 



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

 malaria, which it stains blue. It may be used for the detec- 

 tion of bacteria. 



Leishman's stain is the best for working with malaria and 

 all parasitic protozoa, but for ordinary blood-work I person- 

 ally prefer Jenner (perhaps because 1 am more used to it). 

 The practitioner is recommended to choose one process and 

 stick to it. 



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 appli- 

 cation 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 process, 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 film for a quarter of a 

 minute, wash it, and then examine it under the low power of 

 the microscope. If the film is properly stained, the nuclei of 

 the leucocytes will be seen as blue points, which can be dis- 

 tinguished with great ease with the f-inch objective. If they 

 are not visible, the methylene blue must be applied for about a 

 quarter of a minute more and the examination repeated. 

 When the nuclei are seen to be well stained the film is dried 

 and mounted. 



This process gives results which resemble those afforded by 

 Jenner's stain, except that the fine eosmophile granulations in 

 the polymorphonuclear cells are always less obvious and often 

 quite invisible. It is also suitable for malarial parasites and 

 bacteria. 



The practitioner is recommended to practise this method of 

 staining, as it does not require any reagents which are not to 

 be found in every well-stocked surgery. The watery solution 

 of methylene blue which is used as a counterstain for the 

 tubercle bacillus and some red ink are all that are necessary. 



