392 Journal of Applied Microscopy. 



The first solution acts as a mordant, i. e., it does not stain, but prepares the 

 tissue for the action of the second sokition. 



Transfer to the iron-aknii from water ; allow this solution to act for two 

 hours ; wash in water five minutes and then stain in the one-half per cent, haema- 

 toxylin ten hours or over night. Rinse in water five minutes and treat for a 

 second time with the iron-alum, which now rapidly extracts the stain. The action 

 of the iron-alum should be watched under a microscope, and when the chromo- 

 somes of karyokinetic figures appear sharply defined, the slide should at once be 

 placed in water and washed for at least an hour, since a very little of the iron- 

 alum, if left in the tissue, will cause the preparation to fade. If staining for 

 details other than nuclei, the slide must be transferred to water as soon as the 

 desired efi^ect is produced. After the washing in water, the slide is passed 

 through the alcohols, cleared in xylol, and mounted in balsam. This stain is 

 excellent for the filamentous algae and fungi and it keeps well in glycerin. For 

 preparations to be mounted in balsam, erythrosin, fuchsin, or orange G make 

 good contrast stains. Apply the second stain after the last washing in water. 

 The second stain should always be very light. 



Chromosomes and centrosomes (" of those plants which have centrosomes ") 

 take a brilliant black and other details, though not brightly colored, often show 

 excellent definition. 



The times given above must not be accepted as final. Many prefer to wash 

 in water for several hours after the first immersion in iron-alum. A plan which 

 has proved convenient and very successful is to put the slide into the iron-alum in 

 the morning, let it wash in water during the afternoon, leave it in the one-half per 

 cent, of hsematoxylin over night, and finish the preparation the next morning. It 

 is a long process, requiring care, patience, and judgment, but it is worth the effort. 



THE CARMINES. 



This group of stains, immensely popular a few years ago, has rapidly lost 

 favor among botanists as newer stains and combinations have appeared. When 

 it is desirable to stain in bulk, nothing has been found which will serve better 

 than the carmines. Only three of these stains will be considered. 



Greenachet-' s Borax Cartninc- — 



Carmine, 3 gr. 



Borax, 4gr. 



Distilled water, 100 cc. 



Dissolve the borax in water and add the carmine, which is quickly dissolved 

 with the aid of gentle heat. Add 100 cc. of 70 per cent, alcohol and filter 

 (^Stir/i/ig). 



Stain from 50 per cent, acohol, twelve to twenty-four hours ; treat with acid 

 alcohol five to ten minutes. After the paraffin has been dissolved out with 

 xylol, the preparation may at once be mounted in balsam, or it may be counter- 

 stained with any stain which forms a good contrast. 



Alum Carmi?ie. — A 4 per cent, aqueous solution of ammonia alum is boiled 

 twenty minutes with 1 per cent, of powdered carmine. Filter after it cools 

 {Lee). 



