CH. X] REAGENTS AND THEIR PREPARATION 359 



572. Chloral hematoxylin. Potash alum, 4 grams; distilled 

 water 125 cc.; hematoxylin crystals T V gram. Boil 5 to 10 minutes 

 in an agate or. pyrex dish. After cooling, add 3 grams of chloral 

 hydrate and put into a bottle. This will stain more rapidly after a 

 week or two if the bottle is left uncorked. It takes from i to 5 

 minutes to stain sections, sometimes a long time. Use after any 

 method of fixation. 



It may be prepared for work at once by the addition of a small 

 amount of hydrogen dioxid (H 2 O 2 ). 



If the stain is too concentrated it may be diluted with freshly 

 distilled water or with a mixture of water, alum and chloral. If the 

 stain is not sufficiently concentrated, more hematoxylin may be 

 added. (Proc. Amer. Micr. Soc., 1892, pp. 125-127.) 



573. Iron hematoxylin. -* For this stain there are three solu- 

 tions: (a) the mordant composed of a 2% aqueous solution of ferric 

 alum (iron-ammonium-persulphate); (b) a 0.5% solution of hema- 

 toxylin (10% alcoholic hematoxylin 5 cc., distilled water 95 cc.); 

 (c) the differentiating fluid is composed of the ferric alum diluted 

 several times. 



The stain can be used after any fixer, and the steps are as follows: 

 (i) mordant with the ferric alum i to 24 hours; (2) rinse the speci- 

 men 10 to 30 minutes in water; (3) stain for 3 to 24 hours in the 

 hematoxylin; (4) differentiate slowly, watching the effect under the 

 microscope. For this dip the slide into the ferric alum in the differ- 

 entiator for a few seconds and then rinse with tap water. When 

 satisfactory wash in running water 15 to 60 minutes. The mordant 

 and stain may be used several times. 



574. Hematein. This is used instead of hematoxylin, as it is 

 believed to give more satisfactory results. Prepare as follows : Put 

 a 5 % solution of potash alum in distilled water and boil or leave in a 

 steam sterilizer an hour or two. While warm add i per cent of hema- 

 tein dissolved in a small quantity of alcohol. After the fluid has 

 cooled add 2 grams of chloral for each 100 cc. of solution. (Freeborn, 

 Jour. Ap. Micr. 1900, p. 1056.) 



575. lodin stain for glycogen. lodin ij gram; iodid of potas- 

 sium 3 grams; sodium chlorid ij grams; water 300 cc. For very 



