184 



PHYSIOLOGY OF NUTRITION 



corresponding increase in the amount of protein phosphorus in the tissues, and 

 it appears that the observed increase in these indigestible proteins is mainly 

 made up of phosphorus-free compounds. 1 



In leaves the formation of proteins indigestible in gastric juice is dependent 

 upon the presence of carbohydrates and upon illumination. Palladin 2 found 

 that such indigestible proteins increase in etiolated bean leaves when these are 

 supplied with saccharose, more of these proteins being formed in light than in 

 darkness. The following table presents the results of two experiments in this 

 connection, the numbers representing milligrams. 



12 3 * 6 6 7 S 9 10 11 12 13 11- 



Fig. 88. — Graphs showing metabolic changes during germination of wheat seeds in dark- 

 ness, n-u-c-l, indigestible protein content; p-r-t, total protein content; c-a-r, carbon dioxide 

 eliminated; s-u, sugar content. 



Nitrogen of Proteins Indigestible in Gastric Juice, Contained in ioo g. of 



Etiolated Leaves 



Freshly Gathered 

 18.6 

 18.6 



After Slx Days on Saccharose Solution 

 ix Darkness in Light 



82.6 166.4 



51. g nS-4 



§7. Alkaloids, Toxins and Antitoxins/ — Plants often contain various poison- 

 ous substances, 3 among which alkaloids and some glucosides are especially 



1 Kovchoff, J., Ueber den Einfluss von Verwundlungen auf Bildung von Nucleoprote'iden in den Pflanzen. 

 Ber. Deutsch. Bot. Ges. 21: 165-175. 1903. Zaleski, W., Ueber den Umsatz der Nucleinsaure in Keim- 

 enden Samen. Ibid. 25 : 349-356. 1907. Idem, Ueber den Aufbau der Eiweissstoffe in den Pflanzen. 

 Ibid. 25: 360-367. 1907. Idem, 1907 (Ammoniakbildung). (See note 4, p. I77-] Ivanov, 1902, 1905. 

 [See note 1, p. 177.] 



2 Palladin, W., Influence de la lumiere sur la formation des matieres proteiques actives et sur 1'energie 

 de la respiration des parties vertes des vegetaux. Rev. gen. bot. 11 : 81-105. 1899. 



3 Gauthier, A., Les toxines microbiennes et animales. Paris, 1896. Briihl, Julius, Die Pflanzenalka- 

 loide. Brauschweig, 1900. Rijnu, J. J. L. van, Die Glykoside; Chemische Monographie der Pflanzengly- 

 koside nebst systematischer Darstellung der kunstlichen Glykoside. Berlin, 1900. Winterstein, Ernst, 

 and Trier, Georg, Die Alkaloide, eine Monographie der naturlichen Basen. Berlin, 1910. Faust, Die 

 tierischen Gifte. 248 p. Braunschweig, 1906. 



T This section is numbered §4 in the German; the numbering of the 7th Russian edition is 

 here followed. — Ed. 



