12 HUMAN PHYSIOLOGY. 



inverting ferment of the small intestine, it undergoes inversion, as previously 

 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 mammalia, 

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

 united with one molecule of water. It is souble in water, insoluble in alcohol 

 and ether. It is dextro-rotary. It requires cupric oxid, 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 bacillus it is decomposed into lactic acid, and finally into 

 butyric acid, as follows: 



C 12 H 22 1J +H 2 0= 4 C 3 H 6 3 

 Lactose. Water. Lactic Acid. 



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



Lactic Acid. Butyric 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. It can also be produced by the action of dilute sulphuric 

 acid on starch. The change is expressed by the following equation: 



2 C 8 H 10 6 +H 2 = C 12 H 22 O n . 

 Starch. Water. Maltose. 



Maltose crystallizes in the formt>f white needles, which are soluble in water 

 and in dilute alcohol. It is dextro-rotary. 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 oxid. 

 Fermentation is readily caused by yeast, but whether directly or indirectly 

 by inversion is somewhat uncertain. 



Osa zones. All the sugars which possess the power of reducing cupric oxid 

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

 pounds termed osazones. The osazones so formed are crystalline in struc- 

 ture, but have different melting points, varying degrees of solubility and 

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

 tinguish one from the other. Of the different osazones, phenyl-glucosazone 

 is the most characteristic, and occurs in the form of lo.ng, yellow needles. It 

 may be obtained from dextrose by the following method: To fifty c.c. of a 

 dextrose solution add 2 gm. of phenyl-hydrazin and two gm. of sodium 

 acetate, and boil for an hour. On cooling, the osazone crystallizes in the 

 form of long, yellow needles. 



