APPENDIX. 295 



then to drain off the water, and put the slide and sections in a warm chamber, 

 hot enough to melt the paraffin, until all the water has been driven off. The 

 sections are then found to have adhered firmly to the slide, and the paraffin 

 can be removed by washing the slide with xylol or immersing it in xylol. If 

 not previously stained they can then be passed through alcohol into stain and" 

 afterwards again through alcohol and xylol, previous to mounting in Canada 

 balsam. 



For single sections it is often sufficient to place them in a drop of water, or 

 water and spirit, on the slide, drain off the water and then keep the paraffin 

 melted until the water has been entirely driven off. 



The following are some of the principal staining solutions and methods of 

 staining for special purposes : 



1. Delafield hcemato.vylin. To 150 cubic centimeters of a saturated solu- 

 tion of alum in water, add 4 cubic centimeters of a saturated solution of 

 hsematoxylin in alcohol. Let the mixture stand 8 days, then decant, and 

 add 25 cubic centimeters of glycerine, and 25 cubic centimeters of methylic 

 alcohol. 



For staining sections add a few drops of this solution to a watchglassful 

 of distilled water. If overstained the excess of colour can be removed by 

 alcohol containing 1 per cent, nitric acid. With long keeping this solution 

 becomes red instead of blue ; a trace of ammonia will restore the requisite 

 colour. 



2. Ehrlich hcematoxylin. Dissolve 2 grammes hsematoxyliii in 100 cubic 

 centimeters alcohol ; add 100 cubic centimeters water, 100 cubic centimeters 

 of glycerine, and 10 cubic centimeters glacial acetic acid. This solution will 

 keep almost indefinitely : it is valuable for staining in bulk, as it does not 

 overstain tissues. For staining sections it is best to dilute the solution 

 either with distilled water or with 30 per cent, alcohol. After the sections 

 have been stained they must be thoroughly washed with tap water. This 

 develops the blue colour of the hsematoxylin. 



3. Kultschitzky hcematoxylin. Dissolve 1 gramme hsematoxylin in a little 

 alcohol, and add to it 100 cubic centimeters of a 2 per cent, solution of acetic 

 acid. This solution is valuable for staining sections of the nervous system 

 (modified Weigert-Pal process). 



4. Kleinenberg hcematoxylin. This serves well for staining in bulk. 

 Saturate 70 per cent, alcohol first with calcium chloride and then with alum, 

 and after filtration add six to eight volumes of 70 per cent, alcohol. 



Take a freshly prepared saturated solution of haematoxylin in absolute 

 alcohol, and add it drop by drop to the above mixture until it is of a distinct 

 purplish colour. 



This solution improves on keeping. It may if necessary be diluted with 

 more of the mixture. 



5. ffeidenhairis method. After hardening in alcohol, or in saturated solu- 

 tion of picric acid and then alcohol, place the tissue for 12 to 24 hours in 

 a ^ per cent, watery solution of hsematoxylin, and then from 12 to 24 hours 

 more in a ^ per cent, solution of yellow chromate of potash. Now place in 

 alcohol, pass through xylol, and embed in paraffin. 



