LEUCOPLASTS — MALTOSE 35 1 



paragin in seedlings of various Leguminosae, particularly in 

 those of Lupinus. Leucin crystallizes in thin plates, which are 

 lighter than water and have the appearance of mother-of-pearl. 

 If sections containing leucin are carefully heated on a slide under 

 a coverglass to a temperature of 170° C, the coverglass will 

 become covered with minute, scale-like crystals, which are doubly 

 refractive and may be studied to advantage by means of the 

 polarizer. The crystals of leucin may also be obtained if sec- 

 tions are treated with alcohol under a coverglass, and the alcohol 

 is then allowed to slowly evaporate. 



Leucoplasts. — For methods of fixing and staining leuco- 

 plasts, see in the last chapter under Acid Fuchsin, Gold Chlo- 

 ride, and Picronigrosin. 



Lignified Membranes. — Lignified membranes are distin- 

 guished from cellulose membranes by their insolubility in cup- 

 rammonia, and by being colored from yellow to brown by 

 iodine or chloroiodide of zinc. One of the most reliable tests 

 for h'gnified membranes will be found in the last chapter under 

 Phloroglucin. Aniline sulphate is also a good test for lignified 

 membranes. The sections are first mounted in a drop of a con- 

 centrated solution of aniline sulphate, and then this is replaced by 

 a drop of concentrated sulphuric acid. By this treatment ligni- 

 fied membranes are stained a golden yellow. 



Lipochromes. — These are yellow and red pigments which 

 are for the most part dissolved in fatty substances within the 

 cells, and which are colored blue by sulphuric or nitric acid, 

 and green by potassium iodide-iodine. 



Magnesium. — To demonstrate the presence of magnesium 

 within plant tissues, sections are placed on the slide in a drop 

 of a solution of sodium phosphate or sodium-ammonium phos- 

 phate, and a little ammonia is added. In the presence of 

 magnesium, crystals of ammonio-magnesium phosphate are 

 then formed, which have a coffin-lid form. When the ash of 

 tissues containing magnesium is treated as above, the crystals 

 are apt to form in x- or *-shaped groups. 



Maltose. — Maltose is a sugar which is produced from starch 



h 



