io TEXT-BOOK OF PHYSIOLOGY. 



C, 2 H 22 O n + H 2 = C 6 H 12 O fl + C 6 H 12 O a 

 Saccharose + Water Levulose-f Dextrose 



Invert Sugar. 



Saccharose is not directly fermentable by yeast, but through the specific 

 action of a ferment, invertin or invertase, secreted by the yeast plant, or the 

 inverting ferment of the small intestine, it undergoes inversion, as pre- 

 viously stated, after which it is readily fermented, yielding alcohol and 

 carbon dioxid. 



Lactose is the form of sugar found exclusively in the milk of the mam- 

 malia, from which it can be obtained in the form of hard, white, rhombic 

 prisms united with one molecule of water. It is soluble in water, insoluble 

 in alcohol and ether. It is dextro-rotatory. It reduces cupric hydroxid, 

 but to a less extent than dextrose. Dilute acids decompose it into equal 

 quantities of dextrose and galactose. Lactose is not fermentable with 

 yeast, but in the presence of the lactic acid baciHus it is decomposed into 

 lactic acid, and finally into butyric acid, as expressed in the following 

 equation: 



C 12 H 22 U + H^o - 4 C 3 H 6 3 



Lactose + Water = Lactic Acid. 



2 C 3 H 6 3 = C 4 H 8 2 + 2C0 2 + 2H 2 

 Latic Acid = Buytric Acid + Carbon + Free 



Dioxid Hydrogen. 



Maltose is a transformation product of starch, and arises whenever 

 the latter is acted on by malt extract or the diastatic ferments in saliva and 

 pancreatic juice. The change is expressed by the following equation: 



2 C 6 H 10 5 + H 2 - C 12 H 22 O n 



Starch. Water. Maltose. 



Maltose crystallizes in the form of white needles, which are soluble in 

 water and in dilute alcohol. It is dextro-rotatory. In the presence of 

 ferments and dilute acids maltose undergoes hydration and decomposition, 

 giving rise to two molecules of dextrose. It has a reducing action on cupric 

 hydroxid. Fermentation is readily caused by yeast, but whether directly 

 or indirectly by inversion is somewhat uncertain. 



Osazones. All the sugars which possess the power of reducing cupric 

 hydroxid are capable of combining with phenyl-hydrazin, with the formation 

 of compounds termed osazones. The osazones so formed are crystalline 

 in structure, but have different melting-points, varying degrees of solubility 

 and optic properties, all of which serve to detect the various sugars and to 

 distinguish one from the other. Of the different osazones, phenyl-gluco- 

 sazone is the most characteristic, and occurs in the form of long, yellow 

 needles. It may be obtained from dextrose by the following method: 

 To 50 c.c. of a dextrose solution add 2 gm. of phenyl-hydrazin and 2 gm. 

 of sodium acetate, and boil for an hour. On cooling, the osazone crystal- 

 lizes in the form of long, yellow needles. 



THE FATS. 



The fats constitute a group of organic bodies found in the tissues of 

 both vegetables and animals. In the vegetable world they are largely 

 found in fruits, seeds, and nuts, where they probably originate from a 



