AND HOW TO USE IT. 243 



balsam and benzole. Where used as a contrast-stain, pour a few 

 drops of the strong solution into a watch-glass, and allow the 

 section to remain in this for about ten minutes. This gives a very 

 transparent brown colour to the nuclei and the margins of the 

 cells, leaving the protoplasm almost unstained. Weigert makes a 

 concentrated aqueous solution by boiling in water, filtering from 

 time to time. He also uses a weak alcoholic solution, and com- 

 bines with other colours. 



Naphthaline Yellow for Bone.— Immerse the sections for 

 three days in Miiller's fluid ; then wash in water, and immediately 

 dip in an alcoholic solution of naphthaline yellow (4 grains to the 

 ounce) ; after eight to ten minutes, remove the sections, and dip 

 in a watery solution of acetic acid (3 per cent.) ; then immerse 

 for about ten minutes in an ordinary solution of ammonia carmine, 

 rendered neutral by exposure to the air. Dip the sections again 

 in the acetic acid in order to set the colour, and then place in 

 alcohol of 80 per cent, and subsequently in absolute alcohol. It 

 is excellent for staining foetal bones, etc. ; specimens thus stained 

 show a matrix of deep transparent chrome-yellow. The young 

 bone-corpuscles and osteoblasts, on the other hand, together with 

 the fibrous tissue, will assume a brilliant rose-colour, thus affording 

 an excellent contrast between formed and non-formed bone. 



duinoleine Blue is dissolved in rectified spirit, and an equal 

 part of water is afterwards added. It is a powerful dye, and is 

 greatly diluted when used. The staining has a distinctive shade 

 in different elements of the tissues. It has a special affinity for 

 fat, which it stains a deep blue (Ranvier). 



Picro-Carmine. — There are so many modifications of this 

 stain that we will only give Miller's (for others, see various text- 

 books on Histology, and Vol. 11. of the Journal of Microscopy'). 

 We would recommend students to purchase this dye ready made, 

 as it is difficult and tedious to make : — Add i part of a saturated 

 solution of picric acid to 2 parts of the 15-grain borax-carmine 

 solution (Arnold's, p. 237). Sections should remain in this about 

 twenty-four hours. Wash quickly in water, then in alcohol, 

 transfer to oil of cloves. Another method is to take Beale's 

 carmine without alcohol, and add picric acid in a similar manner, 



