86 The Microscope. 



with twice its volume of distilled water, to which a trace of 

 alcohol has been added. It is then boiled, and filtered while 

 hot, the resulting fluid being of a clear deep-red color and 

 faintly acid reaction. This, if kept in a cool place, will remain 

 unchanged for a considerable time. Probably a crystal of thy- 

 mol or of chloral hydrate would prolong the period. At the 

 time of using, it is diluted with two or three volumes of dis- 

 tilled water, as it is quite thick when cold. 



This solution stains red all objects hardened in chromic acid 

 or chromium solutions. A beautiful violet stain, which is also 

 more permanent than the red, may be produced as follows : 

 The section is stained for one or two minutes as usual in the red 

 fluid, then washed in distilled water and transferred to a one 

 per cent, aqueous solution of lead acetate. Here it is watched 

 until the red has changed to a lilac, when the specimen may be 

 at once mounted in glycerine, or transferred through alcohol 

 or clove oil to balsam. 



A New Method of Using Hematoxylin. 



The materials necessary for the new method of staining are 

 a \ per cent, solution of hsematoxylin in distilled water, and 

 a \ per cent, solution of bichromate of potash. Small, well- 

 hardened pieces of the organ or tissue to be stained are 

 removed from alcohol to 8-10 cc. of the first solution, and are 

 allowed to remain 8 to 10 hours, after which they are placed for 

 a similar length of time in in the same volume of the second 

 fluid. The object should then have assumed throughout its 

 mass a uniform dark color. The excess of bichromate may then 

 be removed by water, and the specimen placed in alcohol. 

 Here it is kept until wanted, when it may be imbedded in par- 

 affine or any of the usual mixtures, and thin sections made, 

 which are cleared in turpentine or zylol, and mounted in bal- 

 sam. 



By this method the nucleus is stained black, the other tis- 

 sue elements taking a more or less dark gray, or even blackish 

 tint, but with this peculiarity, that the different structures can 

 be easily distinguished one from another by their taking differ- 

 ent tones of gray and black. 



This manner of staining has the important advantage over 



