42 THE MICROSCOPIC PREPARATION. 



4. gm. of borax are placed in 93 c.c. of water, after which 100 c.c. of 

 70% alcohol is added. The mixture is stirred, then allowed to settle, 

 and later filtered. Sections are treated as in the aqueous borax-carmin 

 solution. 



Paracarmin is the carmin stain containing the most alcohol, 

 and is therefore of great value. 



Carminic acid I gm. 



Aluminium chlorid 0.5 



Calcium chlorid 4 



Alcohol, 70% ioo c.c. 



Paracarmin stains quickly, is not liable to overstain, 'and is there- 

 fore peculiarly adapted to the staining of large objects. Specimens are 

 washed in 70% alcohol, with the addition of 0.5% aluminium chlorid 

 or 2.5% glacial acetic acid in case of overstaining (P. Mayer, 92). 



Czocor's Cochineal Solution. 7 gm. of powdered cochineal 

 and 7 gm. of roasted alum are kept suspended in ioo c.c. of water by 

 stirring while the mixture is boiled down to half its volume. After 

 cooling it is filtered and a little carbolic acid added. This fluid stains 

 quite rapidly and does not overstain. Before the sections are placed in 

 alcohol they should be washed with distilled water, as otherwise the alum 

 is precipitated on the section by the alcohol. 



Partsch recommends the following solution of cochineal : Finely pow- 

 dered cochineal is boiled for some time in a 5% aqueous solution of 

 alum, and filtered on cooling, after which a trace of hydrochloric acid is 

 added. It stains sections in two to five minutes. 



Alum-carmin (Grenacher). ioo c.c. of a 3% to 5% solution 

 of ordinary alum, or preferably ammonia-alum, are mixed with o. 5 gm. to i 

 gm. of carmin, boiled for one-fourth of an hour, and after cooling filtered 

 and enough distilled water added to replace that lost by evaporation. This 

 fluid stains quickly but does not overstain. Wash the sections in water. 



Hematoxylin. Bohmer's Hematoxylin : 



Hematoxylin crystals I gm. 



Absolute alcohol 10 c.c. 



Potassium alum 10 gm. 



Distilled water 200 c.c. 



Dissolve the hematoxylin crystals in the alcohol, and the alum in the distilled water. 

 While constantly stirring, add the first solution to the second. 



The whole is then left for about fourteen days in an open jar or dish pro- 

 tected from the dust, during which time the color changes from violet to 

 blue. After filtering, the stain is ready for use. Sections, either loose or 

 fixed to the slide or cover -slip, are placed in this solution, and after about 

 half an hour are washed with water. If the nuclei are well stained the further 

 treatment with alcohol may be commenced. Should the sections be over- 

 stained, a condition showing itself in the staining of the cell -protoplasm 

 as well as the nuclei, the sections are then washed in an acid alcohol wash 

 (six to ten drops of hydrochloric acid to ioo c.c. of 70% alcohol) until 

 the blue color has changed to a reddish-brown and very little stain comes 

 from the section usually about one to two minutes. They are then 

 washed in tap -water, and passed into distilled water before placing in 

 alcohol. 



