METHODS OF STAINING. 305 



•can hardly fail to obtain good results with the use of Bohmer's 

 hsematoxylin : 



Transfer the sections from the 80 per eent. alcohol in which they 

 have been kept to a dish of distilled water. At first they will float 

 on the surface of the water ; this is a favorable moment for removing 

 all folds and wrinkles. The sections should be manipulated with 

 platinum needles, prepared by fusing a bit of platinum wire into 

 the end of a glass rod. Such needles can be cleaned by heating 

 the wire red in a flame. 



When the sections sink to the bottom of the dish of water, and 

 remain there, it may be assumed that they are free from alcohol. 



Filter about 5 cc. of the hematoxylin into a watch-glass or butter- 

 dish and transfer the sections from the water to the dye. 



Let the sections stain for three minutes by the watch, and then 

 transfer them to a dish of distilled water. At first the sections will 

 have a reddish tint, but as the washing proceeds the color will turn 

 to a pure blue. During the washing the water should be renewed, 

 until finally it acquires no color from the sections and the latter 

 have lost all traces of a red tint. This washing may take several 

 minutes, or even a few hours ; but if good, permanent stains are 

 desired, it is of great importance that it be thorough. This wash- 

 ing completes the actual staining with hsematoxylin, and the sections 

 are then ready for counterstaining with eosin or for dehydration. 



The eosin solution used for diffuse staining is prepared by dis- 

 solving 1 gram of eosin in 60 cc. of 50 per cent, alcohol. Of this 

 solution, about ten drops are added to 5 cc. of distilled water in a 

 small dish ; the sections are stained for about five minutes and then 

 washed in distilled water. They are then ready for dehydration 

 and mounting. The diluted eosin should be thrown away after use, 

 but the hsematoxylin can be filtered back into the stock-bottle. 



Since the hsematoxylin solution improves with age, no exact 

 directions can be given as to the length of time sections should 

 remain in a particular solution. Three minutes will usually yield 

 good results ; but if it is found that the color is too dark, a shorter 

 time should be employed, and vice versa. One soon becomes famil- 

 iar with the staining-powers of the particular solution used. The 

 dishes that have contained hsematoxylin should be washed soon 

 after use, or may be subsequently cleaned with a little hydrochloric 

 acid, all traces of which should then be removed by thorough wash- 

 ing in water. 



20 



