190 BOTANICAL MICROTECHNIQUE 



SOME SPECIAL REAGENTS FOR MICROCHEMICAL 

 TESTS AND TEMPORARY PREPARATIONS 



170. Some special reagents for microchemical tests and temporary preparations . 



A. Alkanet root tincture. Add enough bits of alkanet root to 95% alcohol 

 to color it deep red. The solution serves as a test for oils and resins 

 (Sec. 12), coloring them red. 



B. Ammonia. Ordinary commercial ammonia water is used after treat- 

 ment of sections, etc., with nitric acid to give the xanthoproteic 

 reaction (Sec. 12), coloring proteids yellow or orange. 



C. Chloral hydrate. A solution of eight parts of chloral hydrate in five parts 

 of water by weight forms an excellent clearing reagent for growing 

 points and pollen grains. 



D. Chloroform. Removes oil from sections of seeds which are to be 

 examined for aleurone grains. 



E. Fehling^s solution. This reagent may be bought of dealers in chemicals. 

 It is usually made up in the form of two or three solutions, which 

 are to be mixed only at the time of using. The following formula is 

 convenient, and keeps well in a cool place. Dissolve 34.64 grams pure 

 crystallized copper sulphate in 200 cc. of distilled water. Mix the solu- 

 tion with 150 grams of neutral potassium tartrate dissolved in about 

 500 cc. of a ten per cent solution of sodium hydrate. The whole is 

 then to be diluted with water to 1 liter, and 100 cc. of glycerin added. 

 The solution serves as a test for sugar (Sec. 12). 



F. Millon's reagent. Dissolve metafllic mercury in its own weight of c.p. 

 concentrated nitric acid and dilute the solution with its own volume of 

 distilled water. This reagent swells cell walls and usually colors pro- 

 teids (Sec. 12) a characteristic brick red. 



G. Nitric acid. C.p. nitric acid, slightly or not at all diluted, is used as 

 a test for proteids (Sec. 12). It is also used in Schultze's macerating 

 mixture (see M). 



H. Olive oil. This is used as a mounting fluid for sections of seeds with 

 aleurone grains. 



I. Phloroglucin. 1-5% solutions in water or alcohol are used as a test for 

 lignified tissue (Sec, 12). 



J. Potassium chlorate. This is used as an ingredient of Schultze's macer- 

 ating mixture (see M). 



K. Potassium permanganate. A 4% solution of this compound in water is 

 used as a stain to distinguish roots from stems in very young seedlings. 



L. Safranln. A saturated or sometimes a half-saturated aqueous solution 

 of this stain is valuable for differentiating tissue elements, e.g. in stem 



