LIST OF REAGENTS. 493 



immersion for a short time in acid alcohol improves the 

 effect in the case of some tissues. If the object be dehy- 

 drated rapidly, or by means of alcohol containing picric 

 acid, a double-stained effect may be obtained, some tissues 

 being stained yellow and others red. 



JBRAZILIN. 



Preparation. Prepare the two following solutions A and B. 

 A: 1 grm. iron-alum dissolved in 100 c.c. 70 per cent, 

 alcohol. B : 5 grm. brazilin in 100 c.c. 70 per cent, alcohol. 



Use. For staining sections on the slide or minute organisms 

 (Protozoa, &c). The slides are placed in fluid A for 1-3 

 hours. Then after slight washing in 70 per cent, alcohol 

 in solution B for about 18 hours. They are then dehy- 

 drated and mounted. 



GRENA CHER'S HEMATOXYLIN. 



Preparation. 24 c.c. saturated solution of Hematoxylin in 

 absolute alcohol, 900 c.c. saturated solution of ammonia- 

 alum in water. Add these together and allow to stand for 

 a week and filter. Then add 150 c.c. pure glycerin and 

 300 c.c. 90 per cent, alcohol. It improves with keeping. 

 For whole mounts dilute with 30 per cent, spirit. Surplus 

 stain may be carefully removed by acid alcohol of half the 

 usual strength. When the required depth of stain is 

 obtained, transfer the object to 70 per cent, alcohol which 

 contains a trace of ammonia, to neutralise the acid. 



MEYER'S ACID H^EMALUM. 



Preparation. Dissolve 1 grm. hsematein in 50 c.c. 90 per cent, 

 alcohol. Dissolve 50 grms. alum in 1 litre distilled water. 

 Mix and allow to settle. Add 20 c.c. glacial acetic acid 

 and a crystal of carbolic acid or thymol. 



Use. For staining tissues in bulk or sections on the slide. In 

 either case the object must be brought down to water, and 

 after staining washed in 1 per cent, alum-solution. 



It is preferable to Kleinenberg's solution in being (1) 

 of definite composition, (2) less affected by light, and (3) 

 keeps better. 



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