ADDITIONS. 395 



sodium hyposulphite, after the required degree of 

 reduction has taken place. The sodium hyposulphite 

 must be thoroughly washed out with water. 



Delafield's hsematoxylin, 



Make (1) A saturated solution of hsematoxylin in 

 absolute alcohol. 



(2) A saturated solution of ammonia alum in 

 the cold. 



Add 4 c.c. of (1) to 150 c.c. of (2), leave for a week, 

 filter, to the filtrate add 25 c.c. glycerine and 25 c.c. 

 of methyl-alcohol. 



This is often called Grenacher's haematoxylin. It stains 

 nuclei well and quickly. To dilute it add some of 

 the mixture minus the hsematoxylin. 



Staining for indirect nuclear division. The tissue 



should be hardened in Flemming's mixture (cp. p. 

 388). The sections are placed in a strong alcoholic 

 solution of safranin, e.g. a saturated solution of 

 safranin in absolute alcohol diluted with an equal 

 quantity of water, and left for a day. They are 

 treated with dilute alcohol and then placed in abso- 

 lute alcohol containing -3 to *5 p.c. hydrochloric 

 acid. In this fluid they are left until colour ceases 

 or nearly ceases to be extracted from them. It is 

 best to examine a section from time to time, when 

 in such a section the cell-substance is decolourized 

 the remaining sections should be removed (twice) to 

 absolute alcohol free from acid. They are then placed 

 in clove oil, and as soon as they become transparent 

 mounted in Canada balsam. Sections may also be 

 stained with Delafield's haematoxylin. 



