146 Modern Microscopy 



glands, hair follicles, and Malpighian layer will then stand 

 out clearly. 



(4) Wash the section well in methylated spirit to remove 

 all traces of the acid, then transfer to some perfectly clean 

 and strong methylated spirit for from ten to fifteen minutes 

 to dehydrate. 



(5) Place some oil of cloves in a watch-glass, take the 

 section from the spirit on a lifter, and carefully float it on 

 to the surface of the oil, in which it must remain for about 

 five minutes. This process is called clearing ; the object of 

 it is to remove the alcohol and to prepare the section for 

 the balsam. 



(6) Transfer the section to some filtered turpentine to 

 wash away the oil of cloves, and mount it in Canada balsam. 

 Sections may be mounted in Canada balsam direct from the 

 oil of cloves, but it is better to wash in turpentine first, 

 because if much oil is mixed with the balsam it will not dry ; 

 the oil also has a tendency to cause the balsam to turn a 

 dark-yellow colour. 



Ehrlich's Haematoxylin. Hgematoxylin 30 grains, 

 absolute alcohol 3J ounces, distilled water 3J ounces, 

 glycerine 3J ounces, und ammonia alum 30 grains. Dis- 

 solve the hsematoxylin in the alcohol and the alum in the 

 water ; mix the two solutions together, and add the 

 glycerine and 3 drachms of glacial acetic acid. The mixture 

 must now be left exposed to light for at least a month, then 

 filter and keep in a stoppered bottle. 



Staining Process. (1) If the specimen has been har- 

 dened in any of the chromic solutions, place the section in 

 & 1 per cent, watery solution of bicarbonate of soda for 

 about five minutes, then wash well in distilled water. If it 

 is a spirit preparation the soda will not be required, but all 

 sections must be washed in distilled water before they go 

 into hsematoxylin stain. 



(2) To a watch-glassful of distilled water add from 10 to 

 20 drops of the haematoxylin solution, and immerse the 

 .section for from ten to thirty minutes. 



