Practical Hints. 221 



shall confine myself to giving the details of two processes 

 which I have found to be so universally successful that I have 

 discarded all others. 



They are a simple carmine staining, and a double staining 

 with carmine and indigo. The carmine solution which I use 

 is one which was published several years ago by Dr. J. J. Wood- 

 ward, in the Lens, and which is made as follows: 



Best Carmine (No. 40,), gr. xv. 



Borax, - - 3 i. 



Water, - - fl. 3 vss. 



Alcohol (95/'e), - fl. 3 xi 



mix and filter, dissolve the crystals in 8 ounces of distilled 

 water, and evaporate over a water bath to 4 ounces. 



Sections placed in this fluid will become stained very evenly 

 in a few seconds, and be of a violet red when removed. They 

 are then immersed in a solution of 



Hydro-chloric acid i part, 



Alcohol - 4 parts, 



until they assume a bright rose color, which appears in a very 



few seconds. The sections are then well washed in several 



changes of alcohol, after which they are ready for mounting. 



A specimen thus treated exhibits only the nuclei with the 

 granules stained, while the cell contents and fibrous tissue are 

 not tinted. This is, in many cases, of great advantage, as a 

 much clearer picture results than if the coloring matter is also 

 seen in the non-nucleated structures, and the nuclei are marked 

 only by a deeper staining. If, however, for purposes of diag- 

 nosis, it is desirable to stain the cell contents also, this can be 

 accomplished by using a concentrated solution of oxalic acid, 

 in alcohol, or, by employing a very weak solution of hydro- 

 chloric acid in alcohol after the specimen has been stained. 



This may also be done, and in a much more beautiful and 

 satisfactory manner, by double staining with carmine and in- 

 digo. Several years ago, when looking at some beautiful 

 double stainings of vegetable tissues prepared by Dr. J. G. 

 Hunt, it occurred to me that a similar effect might be produced 

 in animal tissues, and I immediately commenced to experiment 

 with various colors and dyes. These experiments were only 

 partially successful, and I was about to give them up as im- 

 practicable, when a process was published b}^ Drs. Norris and 

 Shakespear, which promised all that I desired. On working 



