ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
125 
toxylin, prepared as directed below, made in February of tbo present 
year, is at present writing, after eight months, as good as when first 
made. During the eight months it has remained in the laboratory, and 
has been subjected to all the vicissitudes of heat, dust, &c., that an 
ordinary histological reagent must endure. The bottle has no deposit 
upon it, and the solution is entirely devoid of the spores or mycelium of 
fungi, and is in fact as good as when first made. Formula : — Distilled 
water, 300 ccm. ; potash alum, 10 grm. ; chloral hydrate, 6 grin. ; 
haematoxylin crystals, 1/10 grm. 
To prepare the solution, place the water in an agate or porcelain 
dish and add the alum either in powder or small pieces. Boil the water 
and alum for five minutes. When cool add the chloral hydrate and the 
haematoxylin. It is advantageous to dissolve the haematoxylin* in 5 to 
10 ccm. of absolute or 95 per cent, alcohol before adding to the alum 
solution. 
The colour will be quite light at first, but in a week or two it will 
be of a dark purple. The boiling is to destroy all living objects in the 
water or alum, and the chloral hydrate is to prevent the development of 
germs that accidentally reach the solution after its preparation. The 
solution may be made more concentrated by adding haematoxylin. For 
slight dilution, distilled water will answer, but the mixture of alum, 
chloral, and water is the best diluent.” 
