A Text-Book of Physiological Chemistry

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. THE CARBOHYDRATES. We designate with this name bodies which occur especially abundant in the plant kingdom. As the protein bodies form the chief portion of the solids in animal tissues, so the carbohydrates form the chief portion of the dry substance of the plant structure. They occur in the...
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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. THE CARBOHYDRATES. We designate with this name bodies which occur especially abundant in the plant kingdom. As the protein bodies form the chief portion of the solids in animal tissues, so the carbohydrates form the chief portion of the dry substance of the plant structure. They occur in the animal kingdom only in proportionately small quantities either free or in combinations with more complex molecules, forming compound proteids. Carbohydrates are of extraordinarily great importance as food for both man and animals. The carbohydrates contain carbon, hydrogen, and oxygen. The last two elements occur in the same proportion as they do in water, namely, 2:1, and this is the reason why the name carbohydrates has been given to them. This name is not quite pertinent, if strictly considered; because even though we have bodies, such as acetic acid and lactie, which are not carbohydrates and still have their oxygen and hydrogen in the relationship to form water, nevertheless we also have sugars (rhamuose, C.HO, ) which have these two elements in another proportion. Heretofore it was thought possible to characterize as carbohydrates those bodies which contained 6 atoms of carbon, or a multiple, in the molecule, but this is not considered valid at the present time. We have true carbohydrates containing less than 6 and also those containing 7, 8, and 9 carbon atoms in the molecule. The carbohydrates have no properties or characteristics in general which differentiate them from other bodies; on the contrary, the various carbohydrates are in many cases very different in their external properties. Under these circumstances it is very difficult to give a positive definition of carbohydrates. From a chemical standpoint we can say that all carbohydrates are aldehyde or ketone..