APPENDIX A 251 



and then, with either oil of cloves, turpentine and creosote, or 

 cajeput oil ; it is also used for sealing up slides. 



Cane-Sugar. The concentrated solution in water is sometimes 

 used, together with strong sulphuric acid, as a test for proteids. 

 A dilute solution (i per cent., or more) is useful for mounting 

 living cells for observation under the microscope. 



Carbolic Acid (see Phenol). 



Carmine. The two best preparations of carmine are those 

 of Beale and Thiersch. 



1. Beale's Carmine. To prepare this, o'6 gramme of carmine 

 is dissolved in 2 c.c. of boiling solution of ammonia ; the solu- 

 tion must then stand for an hour or so to cool, and to allow of 

 the escape of the superfluous ammonia ; to the solution are 

 added 60 c.c. of distilled water, 60 grammes of glycerine, and 15 

 grammes of absolute alcohol. The mixture must be allowed to 

 stand for some time ; it is then to be filtered. 



2. Thiersch's Carmine. 4 grammes of borax are dissolved in 

 56 c.c. of distilled water ; to this I gramme of carmine is added, 

 and then twice its volume of absolute alcohol is added to the 

 liquid. After filtration the liquid is ready for use. 



Carmine has but little differentiating power : it readily stains 

 the protoplasm and the nucleus ; Thiersch's preparation is espe- 

 cially useful for bringing out the structure of the nucleus. It 

 can very well be used for sections which have been previously 

 treated with picric, chromic, and osmic acids. The time during 

 which the section is to be exposed to its action varies very 

 much ; the rule is that the most satisfactory results are obtained 

 by a prolonged immersion in a dilute solution. In case of over- 

 staining, the section may be washed for a moment in water to 

 which a trace of ammonia has been added. 



Preparations stained with carmine are best mounted in 

 glycerine. (See also Picro-carmine.) 



Chloral Hydrate is used, together with iodine, for the detec- 

 tion of starch-grains included in the chlorophyll-corpuscles. 

 Dissolve 8 parts chloral hydrate in 5 parts of water, and add 

 crystals of iodine, which will dissolve slowly and colour the solu- 

 tion. The material to be tested should be bleached with alcohol, 

 and then be laid in the solution for twelve to twenty-four hours. 



