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a IRew Stalnino flDetbob. 



By J. W. Gatehouse, F.I.C 



IN the last number of the Journal I perceive Kukenthal's 

 staining method is given. Having used this, to some extent, 

 during the preparation of sections in illustration of the 

 papers on *' Development of the I'adpole," which recently- 

 appeared in this periodical, it was found to possess two disadvan- 

 tages : — Firstly, several of the colours, especially the blues, were 

 not permanent, but were obliged to be prepared shortly before 

 use, as otherwise the solutions became colourless, although the 

 object when once obtained retained its colour admirably. 



Secondly, owing to the exigencies of my particular work, the 

 slides were previously coated with a solution of bleached shellac 

 in preference to collodion, as the former could be melted at any 

 period after their preparation, whereas collodion soon set and 

 became useless ; like the solution, each slide requires covering 

 immediately before use. 



Now, with the shellac process, the blue stains obtained by 

 Kukenthal's method unfortunately stained the shellac ground as 

 well as the object, thus rendering the slides unsightly. 



Under these conditions the following method was found to 

 work well. Take the filtered oil of Turpentine and saturate it 

 with Picric acid, adding the acid gradually till a fine, yellow colour 

 has been obtained, and scales of the acid remain undissolved. 

 To this solution add, carefully, crystals of re-sublimed Iodine, 

 taking care to add only a few at a time, as otherwise the chemical 

 action set up may possibly produce sufficient heat to ignite the 

 turpentine, and even cause a slight explosion. With all due care 

 even a series of small decrepitations may be noticed as the 

 Iodine dissolves. Sufficient Iodine should be added to change 

 the colour of the solution from a light yellow to a distinct brown 

 tint ; this solution, when used on embryonic tissues, is capable of 

 differentiating cartilage, muscle, and nerve tissues, especially the 

 grey matter of the brain, which it turns brown, whilst remaining 

 structures take various shades of yellow, or yellow and brown 

 mixed, according to their composition. 



