THI: FOOD OF PLANTS. 83 



dioxide and water. These foods are mainly 

 nitrogen and mineral matters. They arc 

 usually obtained from the soil, being taken up, 

 dissolved in water by the roots. This watery 

 fluid which permeates the plant is known as 

 the sap, and is in constant circulation owing to 

 the evaporation which we now know goes on 

 from the leaves. As the result of this circula- 

 tion the mineral bodies taken up in the sap by 

 the root are carried all over the plant and, 

 combining with the substances formed in the 

 leaves are enabled to play their proper part 

 in the nourishment and growth of the plant, 



5. Thus we see the leaf is one of the most 

 important organs of the plant. By their leaves 

 plants breathe, and also obtain a large amount 

 of their food. The transpiration from the 

 leaves maintains the circulation of the sap, 

 thereby ensuring fresh absorption of mineral 

 matters by the root. 



PRACTICAL WORK. 



1. Kxamine leafy shoots of, for instance, 

 mango, hibiscus, cmton, bread-fruit, tamarind 

 and any grasses, paying special attention to 

 the leaves. Observe that all these leaves have 



