ON STAINING SECTIONS WITH MAGENTA. 141 



prefer the second. They are both prepared with suf^ar. Make 

 a strong syrup and add to it, while hot, 3 to 4 per cent, of 

 either sodium chloride or, what is better, calcium chloride. The 

 first, or common salt syrup, does not readily crystallize, but 

 will do so if left exposed to the air too long (a week or so) ; 

 the second, or calcium chloride syrup, crystallizes with much 

 greater difficulty — in fact, is practically uncrystaliizable. 

 Both are very much concentrated by exposure to air, and 

 become quite as dense as glycerine ; both mix readily with 

 water and exercise no action on tissues beyond rendering 

 them transparent. Neither fluid seems so liable to grow 

 fungi as ordinary syrup, and, as far as my experiments go, I 

 believe the growth of fungi may be entirely prevented by 

 boiling in the water one or two pieces of white pepper. I 

 have kept the syrup through the whole summer without a 

 single fungus making its appearance. If ordinary sugar is 

 employed in making the syrup it is always good to filter it 

 before use. 



Besides preserving specimens stained with magenta very 

 well, I have found these syrups of great service in all cases 

 where glycerine is employed. 



As to the staining fluid, I use one of two modifications — 

 either the simple alcoholic solution, or the fluid obtained by 

 adding water short of precipitation. The best way is to add 

 the water slowly till a slight opacity appears in the alcoholic 

 solution, then alcohol drop by drop till it becomes clear again, 

 but for most purposes the alcoholic solution answers very 

 well. When a specimen is kept for some time in a rather 

 dilute staining fluid, I have found that the effect produced is 

 much better than when it is rapidly stained in a strong one. 

 In fact, nuclei and cells are most stained, as by Beale's 

 carmine. As soon as the preparation is stained it is to be 

 thoroughly washed with water, which sets the colour at once. 

 It is then soaked and mounted in the syrup, which can be 

 used of any degree of concentration suitable to the tissue. 

 A little of the colouring matter oozes out of the interstices of 

 the tissue very often, but not from the tissue itself. 



I generally mount the specimen on a slide, and, if thick, 

 in a cell, and seal the thin glass with dammar varnish or 

 Brunswick black. 



Specimens thus prepared and mounted have been kept for 

 more than a year. The colour is quite unchanged, and they 

 have become very transparent from their long soaking in 

 syrup. 



VOL. XIV. NEW SER. 



