I40 



PHYSIOLOGY or NUTRITION 



§2. Proteins.— The proteins are chemically the most complicated consti- 

 tuents of the plant. 1 They accumulate to the greatest extent in the protoplasm 

 of resting cells and cells where physiological activity is just beginning. The 

 diagrams of Fig. 85 represent stages in the development of a dicotyledonous 

 seedling: 7 is a young embryo, II is a developed embryo, and /// is a germinated 

 seedhng. The parts rich in proteins are shown in black. These parts are the 

 youngest organs of the plant, and are either in the resting condition or are just 

 beginning to grow. The shaded areas represent parts containing smaller 



Fig. 85. — Diagrams showing stages in the development of a dicotyledonous seedling, and 

 distribution of proteins. {After Sachs.) 



^ For the literature of proteins see: Hammarsten, O., Lehrbuch der physiologischen Chemie. 4 te Aufl' 

 Wiesbaden. 1899. [Idem A text-book of physiological chemistry. Tr. by J. A. Mandel from 8th Ger. ed- 

 (7th Eng. ed.) New York, 1914.] Haliburton W. D. A text-book of chemical physiology and pathology. 

 874 p. London, 1891, Seep. 111-142. Cohnheim, Otto, Chemie der Eisweisskorper. 315 p. Braun- 

 schweig, 1900. Griessmayer, Victor, Die Proteidc der Getreidearten. Heidelberg, 1897. [Czapek, F., 

 Biochemie der Pflanzen. i te Aufl. 2 v. Jena. 190S. Idem, same title. 2 te Aufl. Jena, 1913. (Only 

 1st V. (828 p.) has appeared.)] Abderhalden, E., Lehrbuch der physiologischen Chemie in dreissig Vorles- 

 ungen. Berlin, 1906. Idem, Handbuch der biochemischen Arbeitsmethoden. 8 v. Berlin, 1910-1915. 

 [Euler. 1908-1909. [See note 1, p. 139. 1 Hofmeister, 1901. [See note -J, p. 139.] Grafe, 1914. [See 

 note o, p. 77.] Hass and Hill, rci3. [See note 3, p. 6.] Osborne, Thomas B., The vegetable proteins. 

 London and New York, 1909. Plimmer, R. H. Aders, The chemical constitution of the proteins. London 

 and New York. 1908.] 



