176 PHYSIOLOGY OF NUTRITION 



NH— CO NH— CO 



1 



CO C— NH. CH C— NH 



I II >H || || >H 



NH— C W N— C W 



Xanthin Hypoxanthin 



N = C.NH 2 NH— CO 



CH C— NH NH 2 .C C-NR 



II I! >H II I! \ C H 



N € W N C W 



Adenin Guanin 



Among these decomposition products are also the xanthin derivatives, caffein 

 (1-3-7-trimethyl-xanthin) and theobromin (3-7-dimethyl-xanthin 1 )- 



Recent accounts of 'the formation of polypeptids in plants are very inter- 

 esting. 2 These products may be either primary or secondary, the latter being 

 formed by secondary synthetic processes. Tryosin and leucin are among the 

 primary products and are formed by protein hydrolysis due to proteolytic en- 

 zymes. Asparagin, on the contrary, is a secondary product, arising through the 

 transformation of primary products. Tyrosin and leucin, for example, occur 

 only in the first stages of the development of seedlings of Lupinus lulens, 

 while asparagin practically replaces these substances in later stages. The 

 following analyses 3 of lupine seedlings fifteen and eighteen days old show the 

 increase in asparagin content as the seedlings become older. [The values are 

 percentages on the basis of the total dry weight of the seeds before germination. 



Seedlings Seedlings 



15 Days Old 18 Days Old 



Nitrogen of proteins 1 . 49 1 . 51 



Nitrogen of asparagin 385 4-23 



Nitrogen of other compounds 1.27 o. 77 



Both groups of seedlings are seen to contain similar quantities of proteins, 

 but the amount of asparagin in the older seedlings is greater that that in the 

 younger ones. The increase in asparagin content arises at the expense of the 

 lower decomposition products, the amount of which is seen to be correspondingly 

 decreased. 



The amino acids formed in the primary decomposition of proteins are further 

 transformed without oxidation, and the transformation products thus produced 

 have been called aporrhegmas. 4 Furthermore, methylation and splitting 



! Weevers, Th., Die physiologische Bedeutung des Kaffeins und des Theobromins. Ann. Jard. 

 Bot. Buitenzorg //, 6: 1-78. 1907. 



- Schulze, E., Neue Beitrage zur Kenntnis der Zusammensetzung und des Stoffwechsels der Keim- 

 pflanzen. Zeitsch. physiol. Chem. 47: 507-569. 1906. 



3 Merlis, M., Ueber die Zusammensetzung der Samen und der etiolierten Keimpflanzen von Lupinus 

 augustifolius L. Landw. Versuchsst. 48: 419-454. 1897. 



4 Ackermann, D., and Kutscher, Fr., Ueber die Aporrhegmen. Zeitsch. physio. Chem. 69: 265-272. 

 1910. Ackermann, D., Ueber ein neues, auf bakteriellem Wege gewinnbares, Aporrhegma. Ibid., 69 : 

 273-281. 1910. Engeland, R., and Kutscher, Fr., Ueber ein methyliertes Aporrhegma des Tierkorpers. 

 Ibid. 69: 282-285. 1910. 



