180 CHEMISTRY OF PLANT LIFE 



They are, moreover, the source for the material which goes into 

 some of the secretion groups of organic compounds; as they are 

 easily broken down by various agents of decomposition into 

 nitrogen-free alcohols, aldehydes, and acids, which produce the 

 essential oils, pigments, etc. 



Much, if not all, of their physiological activity is due to their 

 colloidal nature, the importance and effects of which will be more 

 apparent after the chapters dealing with the colloidal condition of 

 matter and with the physical chemistry of protoplasm have been 

 studied. 



References 



ABDERHALDEN, E. "Neuere Ergebnisse auf dem Gebiete der Speziellen 



Eiweisschemie," 128 pages, Jena, 1909. 

 FISCHER, E. " Untersuchungen uber Aminosauren, Polypeptide, und Pro- 



teine, 1899-1906," 770 pages, Berlin, 1906. 



MANN, G. "Chemistry of the Proteids," 606 pages, London, 1906. 

 OSBORNE, T. B. "The Vegetable Proteins," 138 pages, Monographs on Bio- 

 chemistry, London, 1909. 

 PLIMMER, R. H. A. "The Chemical Constitution of the Proteins, Part I, 



Analysis," 188 pages; and "Part II, Synthesis, etc." 107 pages, Mono- 

 graphs on Biochemistry, London, 1917. (3d ed.). 

 ROBERTSON, T. B. "The Physical Chemistry of the Proteins," 477 pages, 



New York, 1918. 

 SCHRYBER, S. B. "The General Characters of the Proteins," 86 pages, 



Monographs on Biochemistry, London, 1909. 

 UNDERBILL, F. P. "The Physiology of the Amino-acids," 169 pages, 13 figs. 



1 plate. Yale University Press, 1915. 



