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 formulae 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 



