SPICES. 61 



(b) MICRO-REAGENTS. 



Of the numerous reagents employed in histological work, the following are most 

 useful in spice examination: 



Distilled water. 



Glycerin, pure and diluted with equal volume of water. 



Absolute alcohol. 



Ether. 



Ammonium hydroxid. 



Potassium hydroxid (5 per cent). 



Chloral hydrate (8 parts in 5 parts of water) . 



Schultze's macerating mixture: Crystallized potassium chlorate mixed with nitric 

 acid as needed. 



lodin in potassium iodid: 0.05 gram iodin, 0.2 gram potassium iodid, and 15 cc 

 water. 



Chlorzinc iodin : Treat an excess of zinc with hydrochloric acid, evaporate to a 

 thick sirup and filter through asbestos. As needed, saturate a small portion of the 

 solution first with potassium iodid and finally with iodin. 



Millon's reagent: Dissolve metallic mercury in its weight of concentrated nitric 

 acid, add an equal volume of water, and decant off the clear liquid as soon as the pre- 

 cipitate settles. 



Ferric acetate or chlorid solution. 



Alkanna tincture, diluted with an equal bulk of water. 



Aqueous solution of safranin. 



Hydrochloric acid (10 per cent). 



Acetic acid. 



(c) PREPARATION OF THE MATERIAL. 



Reduce a portion of the sample to a fine powder in a mortar. Separate another 

 portion into several grades of fineness in sieves of different mesh or by jarring on a 

 sheet of paper. In the coarser grades fragments of a suspicious nature may often be 

 seen with the naked eye or under a simple microscope, which should be picked out 

 with forceps for subsequent examination under the compound microscope. 



((1) EXAMINATION. 



Mount a small amount of the ground sample in water and examine under the 

 compound microscope with both ordinary and polarized light. This gives a general 

 insight into the nature of the material and serves for the detection and identification 

 of starch granules and various tissues. 



Draw a small drop of iodin solution into the same preparation by means of a 

 piece of filter paper placed on the opposite edge of the cover glass and examine. 

 Starch granules will be colored blue or blue-black, cellulose yellow, and proteids 

 either brown or yellow. 



In the manner described draw a little potassium hydoxid solution under the cover 

 glass and examine once again. This treatment gelatinizes the starch granules, dis- 

 solves the proteids, saponifies the fats, and in other ways clears the preparation. It 

 also imparts to tannins a reddish color. 



If treatment with potash does not clear the tissues satisfactorily, treat a fresh por- 

 tion for some hours with chloral hydrate solution. 



Examine also the crude fiber obtained in the chemical anaylsis, as in this material 

 the stone cells mid other tissues are beautifully distinct. a 



To isolate stone cells, bast fibers, and other thick- walled cells macerate a portion 

 of the sample in Schultze's liquid, using such proportion of potassium chlorate and 



Winton, Conn. Agr. Expt. StH. Kept., 18%, p. 34. 



