DATISCIN DULCITE 343 



Cytisus laburnum and of other species of Cytisus and in species 

 of Laburnum, Genista, Ulex, Sophora, Thermopsis, Baptisia, 

 Anagyris, Lotus, Colutea and Euchresta. It occurs in less abun- 

 dance in other parts of the plant, such as the petals and per- 

 ipheral tissues of the stem. Potassium iodide-iodine produces 

 with it a reddish-brown, granular precipitate which is soluble in 

 sodium hyposulphite. Chloride of iron gives an orange-red 

 color with cytisin. With phospho-molybdic acid a light yellow 

 precipitate is produced, and picric acid when added to thin sec- 

 tions containing cytisin produces crystal groups of a reddish- 

 yellow color. 



Datiscin, C 21 H 22 O 12 . This glucoside is found in the cell- 

 walls of the wood and bark of Datisca cannabina. Lime and 

 baryta waters produce with it a yellow solution which loses its 

 color on the addition of acetic or dilute hydrochloric acid. In 

 the presence of datiscin, acetate of lead and chloride of zinc pro- 

 duce a yellow, oxides of copper a greenish, and chloride of iron 

 a dark bluish-green, precipitate. 



Dextrine, C 12 H 20 O 10 . This carbohydrate is one of the inter- 

 mediate products between starch and maltose (see Amylose). 

 It is easily soluble in water, and from its aqueous solution it may 

 be precipitated by strong alcohol. It is not colored blue by 

 iodine, and does not reduce salts of copper. 



Dextrose (Glucose, Grape-sugar). See under Glucose. 



Diastase. To demonstrate the presence of diastase in sec- 

 tions they are laid for a time in a dark brown solution of guaiacum 

 in absolute alcohol. When the sections are completely infil- 

 trated with this solution the alcohol is allowed to evaporate, and 

 then the sections are placed in a rather dilute solution of hydrogen 

 peroxide. By this treatment cells containing diastase are colored 

 a beautiful blue. See also under Diastase Solution in the last 

 chapter. 



Dulcite, C 6 H 14 O 6 . Dulcite may be demonstrated in sections 

 from one-year-old stems of Euonymus japonicus. The sections 

 are placed on a slide in a few drops of alcohol, and covered with 

 a coverglass. After the alcohol has slowly evaporated from 



