I$2 MICROMETRY AND BLOOD PREPARATIONS. 



While the Romanowsky methods are more satisfactory for differential 

 counts and for the demonstration of the malarial parasites, and es- 

 pecially for differentiating species, yet by reason of the liability to 

 deterioration in the tropics of methylene blue the haematoxylin methods 

 may be preferable. Many workers in blood-work and cytodiagnosis 

 prefer the haematoxylin. 



1. Fix the film either by heat or with Whitney's fixative. 

 Heat is to be preferred. 



2. Stain with Meyer's hemalum or Delafield's haematoxylin 

 for from 5 to 15 minutes according to the stain. Fre- 

 quently 3 minutes will be found sufficient. To make the 

 hemalum, dissolve .5 gm. of haematin in 25 c.c. of 95% 

 alcohol. Next dissolve 25 gm. of ammonia alum in 500 

 c.c. of distilled water. Mix the two solutions and allow to 

 ripen for a few days. The stain should be satisfactory in 

 2 or 3 days. 



To make Delafield's haematoxylin, dissolve i gm. of 

 haematoxylin crystals in 6 c.c. of 95% alcohol. Add this 

 to 100 c.c. of saturated aqueous solution of ammonia alum. 

 After exposure to light for a week, the color changes to a 

 deep blue-purple. Add to this ripened stain 25 c.c. of 

 glycerin and 25 c.c. of methyl alcohol and, after it has 

 stood for about two days, filter. The stain should be 

 filtered from time to time as a sediment forms. This 

 makes a stock solution which should be diluted 10 to 15 

 times with water when staining. 



3. Wash for 2 to 5 minutes in tap water to develop the 

 haematoxylin color. 



4. Stain either with a i to 1000 aqueous solution of eosin or 

 with a 1/2 of i% eosin solution in 70% alcohol. The 

 eosin staining only requires 15 to 30 seconds. 



5. Wash and examine. 



IODOPHILIA. 



This reaction is supposed to be due to the presence of glycogen, 

 especially in the polymorphonuclears, in suppurative conditions. 



