34 PRACTICAL HISTOLOGY. 



sufficient; for large pieces, one to two hours. The pieces when 

 fixed become whitish throughout. 



For glands and glandular structures generally, a half-saturated 

 alcoholic solution is most useful, i.e., to 50 cc. of a saturated 

 alcoholic solution add 50 cc. of 70 per cent, alcohol. Vignal 

 recommends that to 100 cc. of this mixture there be added 5 to 

 6 drops of nitric acid. The pieces of glands, 4 mm. cubes, are 

 hardened in one hour or so. The hardening is completed in 

 alcohol. 



N.B. All the corrosive sublimate must be washed out of the 

 tissue by alcohol, not water otherwise the sections will be 

 dotted with small black specks or star-like or needle-shaped crystals 

 of the salt, or the salt may be removed by adding a few drops of an 

 alcoholic solution of iodine to the alcohol used to complete the 

 hardening, or before complete hardening in alcohol it may be 

 steeped for 2-3 days in 70 per cent, alcohol, to which a few drops 

 of tincture of iodine is added. 



The action of the salt may be accelerated by placing the tissues 

 in the fluid heated to 38 C. Sections stain readily with all the 

 usual staining reagents. 



N.B. Do not use metallic instruments to transfer the tissues 

 from one vessel to another. Use glass or wood or horn. 



2. Other Fluids for special purposes are mentioned in the 

 text. 



General Directions on Hardening. 



The tissues should be taken from the body as soon as possible 

 after death, and transferred as soon as possible to the hardening 

 fluid. 



Any blood adhering to the parts may be removed by washing 

 them in normal saline solution. 



With a sharp razor cut the tissues in the same plane in which 

 they are afterwards to be cut for sections. The tissue must be cut 

 into small pieces, i.e., \ to f inch cubes, except in the case of 

 tissues to be hardened in Miiller's fluid. They will harden better 

 if they are small, say i cm. square. 



The best way is to suspend the tissues in the upper half of the 

 fluid, which should always be many times the volume 15-20 

 of the tissue. If it is inconvenient to suspend them, cover the 

 bottom of the jar or wide-mouthed bottle in which they are placed 

 with an old washed rag or blotting-paper to prevent the tissue from 

 resting directly on the glass. 



The liquid must be changed within the first twenty-four hours, 

 and again on the second day, then on the fourth, eighth, and twelfth 



