574 Transactions of the Societij. 



drop or two of glacial acetic acid. Tliis, indeed, may be done 

 previous to submitting sections to the action of the blue stain. 



When the section has acquired the desu'ed depth of colour, 

 which is to be ascertained by lifting it occasionally out of the 

 solution on a sable pencil and placing it in methylated spirit, it 

 should be at once washed in the spirit, and submitted in a thii'd 

 saucer to the action of absolute alcohol to remove all the water 

 imbibed by the section. 



In practice I have found that a light purple tint is sufficiently 

 deep for sections of the spinal cord and of some other tissues. 



From a quarter to half an hour will suffice for the removal of 

 the water by the alcohol. 



The section is now ready for final mounting. Transfer it 

 to a glass slide, and when the spirit has nearly volatilized, clear 

 with clove oil, and mount in one of the dammar solutions. I prefer 

 Klein's solution. 



It must not be supposed that this double-staining process is 

 suitable for animal tissues in general. I merely recommend it as 

 capable of j)roducing excellent didactic results, and when carried 

 out with care will amply repay the histologist for the trouble given 

 to it. 



I should be wanting in gratitude were I to conclude without 

 acknowledging that I am indebted for the blue and the scarlet 

 colours to the courtesy of Messrs. Brooks, Simpson, and Spiller, of 

 50 Old Bond Street, London, who obligingly forwarded to me 

 samples of Atlas scarlet and the blue, both of which are perfectly 

 soluble in water. 



