CELL-CONTENTS AND FORMS OF CELLS. 155 



portant. In this group are also included maltose, formed by the 

 action of diastase on starch and by the action of ferments on 

 glycogen; trehalose or mycose, found in the Oriental Trehala, 

 ergot, Boletus edulis, and other fungi ; melibiose, occurring in 

 Australian manna and in the molasses of sugar manufacture; 

 touranose, found in Venetian turpentine (obtained from Larix 

 europaa) and in Persian manna; and agavose, occurring in the 

 stalks of Agave americana. 



Of the numerous sugars the following are likely to be met 

 with in the microscopical study of drugs and economic products : 



Dextrose (grape-sugar or dextro-glucose) is found in sweet 

 fruits, the nectaries of the flowers, and stems and leaves of various 

 plants. It crystallizes in needles and varies in amount from I to 2 

 per cent, (in peaches), to 30 per cent, in certain varieties of 

 grapes. It also occurs in combination with other principles, form- 

 ing the glucosides. 



Levulose (fructose, fruit-sugar, or levo-glucose) is associated 

 with dextrose, occurring in some instances even in larger quanti- 

 ties than the latter. 



Sucrose (saccharose or cane-sugar j is found rather widely 

 distributed, as in the stems of corn, sorghum and the sugar-cane; 

 in roots, as the sugar-beet; in the sap of certain trees, as sugar- 

 maple and some of the palms ; in the nectaries and sap of certain 

 flowers, as fuchsia, caryophyllus, and some of the Cactaceae ; in 

 seeds, as almond and chestnut, and in various fruits, as figs, mel- 

 ons, apples, cherries. In some plants, as in sugar-cane, the yield is 

 as high as 20 per cent. It crystallizes in monoclinic prisms or 

 pyramids, and forms insoluble compounds with calcium and 

 strontium. 



Maltose is found in the germinating grains of cereals (see 

 Malt) ; it forms colorless, needle-shaped crystals resembling those 

 of dextrose, and forms compounds with calcium, strontium, barium 

 and acetic acid. 



Trehalose occurs in some fungi, as ergot and Amanita mus- 

 caria the latter containing as much as 10 per cent, in the dried 

 plant. 



Mannitol occurs in the form of needles or prisms and is found 

 in the manna of Fraxinus Ornus to the extent of 90 per cent. It 



