OF MICROSCOPIC OBJECTS. 165 
nerve-tissue in a mixture of glycerine and carbolic acid in 
the proportion of fifteen of the first to one of the second. 
To mount these sections, they must now be steeped in pure 
spirit for two hours, and afterwards in oil of turpentine, and 
lastly must be mounted in Canada balsam. 
Dr. Lionel Beale recommends the use of chloride of gold 
for colouring nerve fibres. A solution containing from 2 to 
1 per cent. in distilled water should be made. The tissue 
having been soaked in it until it becomes straw-coloured, is 
to be washed, and then placed in very dilute acetic acid 
containing one per cent. or less. The nerves exhibit a blue 
or violet tinge on exposure to light for a few hours. He 
speaks also of solution of osmic acid for the same purpose, 
1 part to 100 of water, but not with much approval. The 
aniline colours, such as magenta and solferino, may, accord- 
ing to the same authority, be also employed for most tissues. 
They are not very soluble in water, but are readily dissolved 
by alcohol. A grain of the colour, 10 to 15 minims of 
alcohol, and an ounce of distilled water, make a dark red or 
blue (purple) solution which colours tissues very readily. 
For these and many other useful formule for the same pur- 
pose, the reader may consult “ Beale on the Microscope.” 
Dr. Klein, in No. 40 of the Monthly Microscopical Journal, 
in order to demonstrate the nerves of the cornea, takes that 
of the rabbit or guinea-pig, a quarter or half an hour after 
death, and places it in a half per cent. solution of chloride 
of gold, for from one and a half to two hours—that of the 
guinea-pig for an hour to an hour and a quarter. After 
that, the cornea is washed in distilled water, and exposed to 
the light in distilled water for from 24 to 36 hours (the 
water being changed twice, or oftener). After this time has 
elapsed, the cornea is transferred into a mixture of one part 
pure glycerine and two of distilled water, where it remains 
for two or three days. Up to this time the cornea has not 
assumed a darker colour than ash-grey, perhaps having a 
violet tint; at all events the whole of the cornea is trans- 
parent. It is then brushed over on its anterior surface 
