30 THE AMERICAN MONTHLY [February, 



I have found the following preparation of carmine to be very useful for 

 staining both germinal matter and formed material of animal sections : — 



I grain carmine, 

 25 cc. water, 

 3 cc. ammonia. 

 Dissolve the carmine in the ammonia ; then add the water ; filter and pre- 

 serve in a stoppered bottle. 



' Thiersch's carmine fluid.* — Frey {^Das Mikroskop) gives Thiersch's 

 fluid for coloring tissue by carmine : — 



Carmine, i part ; 

 Caustic ammonia, i part; 

 Distilled water, 3 parts. 

 This solution is to be filtered. 



Oxalic acid, i part; 

 Distilled water, 32 parts. 

 One part of the carmine solution is to be mixed with eight parts of the oxalic 

 acid solution, and 12 parts absolute alcohol are to be added. 



If the solution is orange colored, instead of dark red, more ammonia is 

 required, and the orange becomes red. The orange color may also be used 

 for staining. If crystals of oxalate of ammonia become formed, they must be 

 separated by filtration.' 



grenacher's alcohol borax carmine. 



This is useful for staining preparations of Hydroid Zoophytes, Sponges, 

 Annelids, Crustacea, and also for coloring many animal tissues en inasse. 

 Make a four per cent, solution of borax in water, and add an equal quantity 

 of a two and a half per cent, solution of carmine in water. Allow the mix- 

 ture to stand for three days, and then add an equal bulk of 70% alcohol. The 

 liquid must now be allowed to stand again for about a week, when the dark 

 red supernatant portion should be syphoned ofl'from the lower light-colored 

 stratum of precipitated carmine. 



Sections stain in this fluid in a few minutes ; they should be washed in 

 about 60%, dehydrated in 90% alcohol, cleared in clover oil, and mounted in 

 Canada balsam. 



carmine for vegetable tissues. 



i^ grms. carmine, 



5 cc. ammonia, 

 95 cc. water. 

 Dissolve the carmine in ammonia, add the water, filter the mixture, and 

 preserve it in a stoppered bottle. This pi-eparation is useful either in single or 

 double staining. The sections require to be bleached and mordanted. If 

 it is desired to preserve the nuclei, protoplasm, or other cell-contents, the 

 sections must be bleached by placing them in 90"^ alcohol, and keeping them 

 in it until every trace of chlorophyl has been abstracted. They are then 

 placed in w^ater for ten minutes, after which they are transferred to a 2% so- 

 lution of alum in water for twenty-four hours. The action of this mordant 

 is to precipitate the carmine in the tissues of the section in so finely divided 

 a form that the granules are invisible even under the highest powers of the 

 microscope. In investigations on the shape or peculiarities of cell-walls, or 

 the crystalline contents of cells, the following bleaching agent may be used 

 with advantage : — Rub up in a mortar two ounces of fresh chloride of lime 

 with two ovmces of water, and make up the mixture to one pint ; allow it to 



* ' How to Work with the Microscope,' p. no. 



