412 HISTOLOGY. 



method, the very important but complex Weigert stain for myelin, and the 

 iron haematoxyline stain for cytological details are omitted with many 

 others. Since they are so well described in Mallory and Wright's Tech- 

 nique, which the medical student who intends to understand bacteriological 

 and histological methods should possess, it seems best to limit this account 

 to the stains which the beginner may employ. 



Elastic fibers are stained dark purple or almost black with Weigert's 

 resorcin-fuchsin. Other parts of the tissue should be nearly colorless. 

 The stain is prepared by heating until it boils, in an evaporating dish, 2 gr. 

 of fuchsin and 4 gr. of resorcin in 200 cc. of water. Then 25 cc. of 

 liquor ferri sesquichlorati are added and the mixture is boiled for 5 minutes. 

 It is cooled and filtered in order to collect the precipitate. The dish in 

 which the boiling took place is dried, together with whatever precipitate 

 remained in it, and after the precipitate upon the filter paper is also dry it is 

 placed with the paper in the dish. 200 cc. of 95 per cent, alcohol are added 

 and boiled to dissolve the precipitate; the paper is removed. When the 

 solution has cooled it is again filtered to collect the filtrate. 4 cc. of hy- 

 drochloric acid, and enough 95 per cent, alcohol to make up 200 cc. of stain, 

 are added. 



In this solution paraffin or celloidin sections may be stained from 20 

 minutes to an hour; then they are washed in alcohol, dehydrated, cleared, 

 and mounted. It the stain has affected other parts of the tissue than the 

 elastic fibers, the sections should be washed in alcohol containing "a few 

 crystals of picric acid," or in alcohol containing i per cent, of hydrochloric 

 acid. 



White fibers of connective tissue may be stained by Mallory's aniline 

 blue. Fibrils of connective and reticular tissue, amyloid, and mucus 

 stain blue; nuclei, protoplasm, muscle, nerves and neuroglia fibers stain 

 red; red corpuscles and myelin stain yellow. Paraffin or celloidin sections 

 of material fixed in Zenker's fluid are stained 5 minutes or longer in a J-Q 

 per cent, aqueous solution of acid fuchsin. They are transferred directly to 

 a stain consisting of 0.5 gr. of aniline blue soluble in water, and 2 gr. of 

 orange G, dissolved in a 100 cc. of a i per cent, aqueous solution of phos- 

 phomolybdic acid. In this they remain 20 minutes or longer. They 

 are washed in several changes of 95 per cent, alcohol, cleared, and mounted. 



Fat may be stained red in frozen sections of fresh material or of that 

 hardened in formaline, by means of a saturated solution of Scharlach R. 

 in 70 per cent, alcohol. The frozen sections are transferred from water to 

 the stain, which has been filtered and is kept tightly stoppered, since 

 evaporation of the alcohol causes a precipitation of the stain. The sections 

 remain in the stain from 15 minutes to over night; then they are washed in 



