254 THE MICROSCOPE. 



the cord may be kept till wanted for sections. Portions of cord 

 are stained before sections are made by soaking for twelve hours in 

 a solution of good picro-carmine. Wash in weak spirit, and soak 

 for a short time in absolute alcohol, which should be used to wet 

 the razor in cutting. Clear in clove oil, and mount in dammar or 

 Canada balsam dissolved in benzole. This way of staining in 

 picro carmine before cutting enables one to trace the processes, 

 cells, etc. The best picro carmine is made by MM. Rousseau 

 and Son, Paris, or Martindale. The only objection to the ammo- 

 nium-bichromate method is that the solution is liable to deposit 

 in the form of small specks amongst the nerve. 



Spirit and Iodine Mixture and Ammonium Bichromate.— 

 Place the cord in a long glass tube of rectified or methylated 

 spirit, made slightly brownish with tincture of iodine for three or 

 four days, or until the iodine colour has vanished. Cut into 

 pieces about half-an-inch long, and place them in three times their 

 bulk of a 2 per cent, watery solution of ammonium bichromate 

 for four to five weeks, and transfer to spirit until required. 



I have found Dr. H. Gibbe's Double Stain to show cells, nuclei, 

 etc., well, and it is pleasant to work with. 



Beck's New "Purple" stains nuclei well, and brings out 

 minute vessels. It is a slow process, and requires a good deal of 

 washing in spirit, and is therefore not a very handy stain. 



Coppock's Magenta and Aniline is a very ready stain, diffe- 

 rentiates the several structures, and is easily dehydrated with 

 clove oil. 



Anilin Blue Black, according to the depth of tint employed, is 

 good for the differentiation of structure. It brings out well the 

 cells from the neuroglia. It, however, requires care in adjusting 

 the tint. 



Judson's Cambridge Blue is a convenient form of stain. 



Ink is a very good stain, more especially for the cells of 

 Purkinje in the brain. 



