TRANSLOCATION AND STORAGE OF FOODS 219 



other amides and amido-acids are among the intermediate nitro- 

 genous compounds from which proteins are ultimately con- 

 structed with the aid of previously-formed carbohydrates. 



The construction of proteins from asparagine and sugars appears 

 in certain cases, to take place in the leaves and may go on in 

 the dark, but in some instances the process is favourably in- 

 creased when the plants are exposed to the light. Similar 

 manufacture of proteins occurs in roots and probably in other 

 parts of plants. 



Schultze and others have shown that plants can utilize nitrates 

 and ammonium salts for the manufacture of asparagine and allied 

 amido-compounds. According to Suzuki, the conditions for 

 the formation of asparagine from nitrates are a somewhat high 

 temperature and the presence of sugar. 



Besides being produced synthetically from absorbed nitrates or 

 ammonium salts and sugars, asparagine is apparently produced in 

 plants by the decomposition of proteins, and this asparagine can 

 be utilised again for the regeneration of proteins when a suitable 

 supply of carbohydrates is present to complete the synthesis. 



In addition to nitrates, other inorganic compounds such as 

 sulphates and phosphates take a part in the formation of proteins, 

 for the latter contain sulphur and sometimes phosphorus as well ; 

 probably some of the metallic elements, such as potassium and 

 calcium, which are known to be essential for proper nutrition 

 of plants, are also more or less directly indispensable to the 

 formation of complex proteins. 



3. Utilisation, translocation and storage of plant-foods. — 

 The various organic compounds manufactured, by anabolic 

 processes are utilised in different ways. A certain amount of 

 sugars and fats are consumed in the respiration-process, and in 

 the case of plants grown in the dark and in the earliest stages of 

 the growth of seeds, tubers and bulbs, the destructive respiratory 

 process results in a considerable loss of carbon which is given 

 off as carbon dioxide into the air ; under such conditions there 



