542 POWDERED DEUGS 



The amount of the fixative employed should always be large in proportion to 

 the material to be fixed in it. 



A corrosive sublimate fixative which may be used cold or hot, as the material 

 may require, is prepared by mixing 80 parts of a saturated aqueous solution of 

 corrosive sublimate with 200 parts of glacial acetic acid. As with all aqueous fixa- 

 tives, the air-pump should be employed when this fixative is used cold. 



Fuchsin. See under Double Staining. 



Fuchsin, Acid. Excellent for staining crystalloids. The material containing 

 the crystalloids should be fixed in a concentrated alcoholic solution of corrosive sub- 

 limate. Then the sections should be immersed for twenty-four hours in a 0.2 per 

 cent, solution of acid fuchsin, to which a little camphor has been added. To demon- 

 strate crystalloids in chromatophores the sections should be treated as follows : The 

 sections are placed in a solution of 20 per cent, acid fuchsin in 100 Gm. of aniline- 

 water. This solution is heated somewhat while the sections remain in it from two 

 to five minutes; they are then rinsed in a solution of I part of a concentrated solu- 

 tion of picric acid in alcohol and 2 parts of water. This solution should be warmed 

 to about 40 C., and the sections should be rinsed in it until they cease giving off 

 color to it. Thereafter they are dehydrated in strong alcohol, passed into xylol, 

 and mounted in Canada balsam. 



Acid fuchsin is an excellent stain for leucoplasts and chromatophores in general. 

 The material is fixed in a concentrated alcoholic solution of corrosive sublimate in 

 absolute alcohol, where the material remains for twenty-four hours ; then the fixa- 

 tive is washed out in alcohol containing iodine (see under Fixatives). Sections from 

 this material are placed in a 0.2 per cent, solution of acid fuchsin in distilled water. 

 After remaining twenty -four hours they are taken out, washed in running water 

 for a time, and are then examined in glycerine or are allowed to dry, after which 

 they are mounted in Canada balsam. The sections can not be dehydrated in 

 alcohol, because this will extract the stain from the chromatophores. The follow- 

 ing method may also be used: The material is fixed in a solution of 5 Gm. of corro- 

 sive sublimate in 100 Gm. of absolute alcohol, which is acidulated with 10 drops of 

 hydrochloric acid. Then the fixative is removed by placing the material in pure 

 alcohol, which is several times replaced. Sections from this material should be 

 stained by immersion for about twenty minutes in a solution of 2 Gm. of acid 

 fuchsin in 200 mils of distilled water and 3 mils of aniline oil. They are then washed 

 in a mixture of 50 mils of a saturated alcoholic solution of picric acid and 100 mils 

 of water until color ceases to be given off from the sections. Then the picric acid 

 is washed from the sections in pure alcohol. The sections are next placed in 

 chloroform for ten minutes and are then ready to be mounted in Canada balsam. 



When desired, sections cut from fresh material may be fixed and stained as 

 above. Or the material may be fixed and imbedded, and after microtome sections 

 have been cut and mounted on the slide they may be stained as above directed. 



A beautiful double stain for nuclei is prepared from acid fuchsin and methyl 

 blue as follows: The microtome sections mounted on the slide are immersed for half 

 an hour in a o.ooi per cent, aqueous solution of acid fuchsin, then quickly washed in 

 water, and immersed for about one minute in a 0.002 per cent, aqueous solution of 

 methyl blue. The surplus stain is then washed off in alcohol and the preparation 

 is allowed to dry; then the sections are immersed in olive oil from six to twenty-four 

 hours, after which they are washed in absolute alcohol or in a mixture of absolute- 

 alcohol and xylol until the stains are quite clear, and the preparation is ready to be 

 mounted in Canada balsam. 



Gelatine. Motile swarm spores and the like are sometimes mounted for 

 observation in a solution of gelatine, which renders their movements less rapid, 



