Ch. X] REAGENTS AND THEIR PREPARATION 359 



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

 water 125 cc; hematoxylin crystals y\ 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 (H2O2). 



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. See, 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- 

 toxyhn (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 S % solution of potash alum in disfiUed 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 i| gram; iodid of potas- 

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



