BLOOD AND GLANDS 417 



minute. Rinse in distilled water and place in hydrobromic 

 (Merck's concentrated, 34 per cent., 1 part ; distilled water, 

 3 parts) for one minute. Hydrobromic acid may be omitted 

 following the use of phosphomolybdic acid. 



Sensitisation. Wash in tap water, then in distilled water and 

 dip in 1 per cent, uranium nitrate (sodium free) for five seconds 

 or less. 



Ivipregnalion. Wash in distilled water for ten to twenty 

 seconds and place in silver diamino hydroxid (Foot) for one 

 minute : — 



To 5 c.c. of 10-2 per cent, silver nitrate add ammonium hydroxid 

 drop by drop until the precipitate which forms is dissolved. Add 

 5 c.c. of 3-1 per cent, sodium hydroxid and just dissolve the 

 resulting precipitate with a few drops of ammonium hydroxid. 

 Make the solution up to 50 c.c. with distilled water. 



Reduction. Dip quickly in 95 per cent, alcohol and reduce 

 for one minute in the following solution : — 



Distilled water, 50 c.c. ; 40 per cent, neutral formalin 

 (neutralised with magnesium carbonate), 0-5 c.c. ; 1 per cent, 

 uranium nitrate, 1-5 c.c. 



Toning. Wash in distilled water and place in 1 : 500 gold 

 chloride (Merck's reagent) one minute. Rinse in distilled water. 

 Place in 5 per cent, sodium thiosulphate (hyposulphite) one to 

 two minutes. 



Counterstaining and Mounting. Wash in tap water ; counter- 

 stain, if desired, with haematoxylin and Van Gieson, or hsematoxylin 

 and eosin ; dehydrate in alcohol. Clear in xylol and mount 

 in balsam. The use of ammonia must be avoided in blueing 

 sections after haematoxylin as it dissolves the silver. 



The use of distilled water and clean glassware for all solutions 

 is essential. All the solutions may be used repeatedly and kept 

 in Coplin jars for several days. The solutions keep without 

 disintegrating in amber glass-stoppered bottles for an indefinite 

 time. 



Another variant is that of Gordon and Sweets {Amer. Journ. 

 Path., xii, 1936, p. 545). It is claimed that this method gives 

 impregnation of the finest fibres, while not requiring precise or 

 rapid changes of the sections from one solution to another. 



1. Fix in 10 per cent, aqueous formalin or in Bouin's solution. 

 2. Cut frozen sections or imbed blocks in paraffin or in celloidin. 

 Affix frozen or paraffin sections to slides by Wright's technique or 

 by Mason's gelatin glue method, or ensheath in celloidin by 

 Warthin's molasses-celloidin sheet method. 3. Oxidise for one 

 to five minutes in acidified permanganate solution : 47-5 c.c. of 

 0-5 per cent, aqueous potassium permanganate plus 2-5 c.c. of 

 3 per cent, sulphuric acid. 4. Wash in water. 5. Bleach until 

 white in 1 per cent, oxalic acid. 6. Wash in tap water and two 



VADE-SIKCUM. 14 



