LABORATORY WORK 



IN 



PHYSIOLOGICAL CHEMISTRY. 



THE CARBOHYDRATES. 



The term carbohydrate is usually considered as embrac- 

 ing those compounds which contain the elements C, H, and 0, 

 the H and being present in the same ratio as they exist in 

 water. This definition, strictly followed, would include in the 

 group substances such as lactic acid, acetic acid, and inosit, 

 which are obviously not carbohydrates. The carbohydrates 

 may be conveniently divided into three groups; namely, 

 Monosaccharides or Glucoses, Disaccharides or Saccharoses, 

 and Polysaccharides or Amyloses; but a more strictly chem- 

 ical classification would designate them according to the 

 number of carbon atoms present in the molecule, the prefix 

 aldo- or keto- denoting to what general class of compounds 

 (aldehydes or ketones) they belong: thus trioses, tetroses, 

 pentoses, hexoses, heptoses, etc., and aldohexose, ketopen- 

 tose, etc. Of the greatest physiological importance are the 

 pentoses, hexoses, hexobioses (Disaccharides), and polyoses 

 (Amyloses). 



Note the general character and appearance of the van- 



