70 The Mickoscope. 



Second, wash them in warm, distilled water or lightly boiled rain 

 water, filtered and clean, from 150° F. to boiling, if sections will 

 bear it — most of them do — say from two to twenty minutes, de- 

 pending on the temperature of the water, when the sections can be 

 stained in carmine. I prefer the ammonia carmine. When time 

 allows, the sections can be soaked in cold water from ten minutes to 

 one hour, or they may be dipped in cold water and dropped into 

 two grades of alcohol, first into say 60 per cent, several minutes, 

 and then into 95 per cent, alcohol to hasten the process, and then 

 dipped into water one or two minutes before staining in carmine. 



TESTING SECTIONS. 



One way to test them is as follows: Lay several washed sec- 

 tions on a slide and let the water (warm preferred) drop on your 

 tongue. If you cannot detect any sour or acid taste they may be 

 considered ready for the carmine stain. The safest way to test them 

 is to let the water drop from a section on to a clean slide and apjDly 

 a little carmine to it and examine under a one or one-half inch ob- 

 jective, and if no precipitation of the carmine stain is visible, you are 

 safe to stain them in carmine. Surest way. of course, is to test every 

 section one by one before di-opping into carmine. I never stain more 

 than from one to six sections at a time, as the same kind of sections 

 don't all work alike, and sometimes finish them on a slide (used for 

 that purpose) and examine them until satisfactoiy. I have found, 

 the Echein green able to resist, in most of sections, the action of ab- 

 solute alcohol and essential oils. When the Echein green fades in the 

 process I stain them as deeply as possible in the Echein green stain. 

 I have found this sufiicient in nearly every instance. When sections 

 are stained too deeply, let them remain longer in the al^solute alcohol. 

 This, with some exceptions, generally reduces the color to the desired 

 shade. Some plant, or wood sections, have such a strong affinity 

 for green stains that, when over- stained, the alcohol cannot, in the 

 least, reduce it to a lighter shade. I have saved such sections (when 

 I had no others) by dropping them in a weak alkaline solution of 

 ammonia, etc.," a short time, which removed the excess of color. If 

 this solution is a trifle too strong, it ruins plant or wood sections, es- 

 pecially delicate ones. Sections treated in this manner must be 

 soaked in distilled water or alcohol until all traces of the alkali is 

 removed, or it will fade the green stain. 



Ammonia carmine too frequently has too much ammonia in it. In 

 such cases the cork should be removed and a piece of fine cambric 

 tied over the mouth of the bottle to keep the dust out and to allow 

 the excess of ammonia to escape, say from two days to a week. I left 



