94 PLANT COMPOUNDS 



existing in but small amounts at any one time. There are 

 a number of these amides and amino-acids found in plants, 

 but the more common ones, and ones which illustrate these 

 compounds very well, are as follows: 



(a) Asparagine is found in considerable quantities in pea 

 and bean seedlings, 



CH2.CO.NH2 

 NH2.CH.COOH 



It is also called amino-succinamide. 



(6) Glutamine occurs to a large extent in cucumber and 

 other seedlings. It is the monamide of amino-glutaric acid, 



CH2.CONH2 



I 

 CH 2 



I 

 NH2.CH.COOH 



(c) Argenine occurs largely in coniferse or trees of the 

 pine order, and possesses a more complicated structure than 

 the others mentioned, 



NH 2 



NH:c/ 



NH . CH 2 . CH2 . CH 2 . CH . COOH 



NH 2 



(d) Tyrosine is an amino-acid of the carbocyclic series, 

 found in many plants, 



CH2.CH.COOH 



v NH 2 



OH 



84. Proteins. — It has already been stated (Section 5) 

 that proteins are compounds containing carbon, hydrogen, 



