PRACTICAL NOTES ON HISTOLOGY. 227 



render the lens brittle and too hard, and often the sections are 

 difficult to stain. This can be done by placing the eye in a 2 per 

 cent, watery solution of carbolic acid for a week, and should then 

 be transferred to alcohol and treated as usual. If sections are 

 required without a lens, use chromic acid solution. The eye is 

 best stained in bulk, though not absolutely necessary. Before 

 placing in the stain four small openings should be made in it: two in 

 the anterior chamber and two in the vitreous. The former should 

 be situated opposite to one another, at the periphery ; the others 

 opposite one another, and situated midway between the cornea 

 and the entrance of the optic nerve. I believe the best reliable 

 stain for bulk is borax carmine (alcoholic). Kleinenberg's log- 

 wood penetrates sufficiently, but often fails to select. Dr. H. 

 Gibbes' logwood, given in April number of The Microscope^ 1889, 

 seems so far, if used in a weak solution, to act tuell. Most of the 

 anilines stain and penetrate admirably, but are partially removed 

 during the necessary after-treatment. The eye should be left in 

 the stain for from two to four days, according to the rapidity with 

 which it stains. The staining is sometimes diffuse, and it is 

 therefore preferable in some cases to place the eye, after staining, 

 in alcohol, containing a trace of hydrochloric acid, in order to 

 remove the stain from everything but the nuclei. For alcoholic 

 borax carmine (Woodward's) take carmine, 15 grains; borax, 

 I drachm; water to make 8 ounces. Dissolve by warming and 

 slowly evaporating to 4 ounces ; now add 7 ounces of alcohol. If 

 used in bulk, there is no need to filter it. Shake well from time 

 to time. When the eye is stained wash it, and transfer it to 

 alcohol, and then to a mixture of equal parts alcohol and ether. 

 In this mixture leave the eye for twenty-four hours, when it 

 should be transferred to a thin solution of celloidin, in equal 

 parts of absolute alcohol and ether; the ether should be the 

 greater of the two if not measured, leaving the solution for two or 

 three days until the mass has penetrated to all parts. Embed as 

 usual, and when the eye is covered place the box on a glass 

 plate, and cover with a bell-jar. The alcohol and ether diffuse 

 into the air beneath the bell-jar, and the celloidin slowly consoli- 

 dates. If a bell-jar is not used, a crust usually forms on the 

 surface of the celloidin, and further evaporation is hindered. 



