20 CROP GROWING AND CROP FEEDING 



carried away and stored for future use, unless at once needed to build walls 

 with. It is stored in roots, in underground tubers like the Irish potato, and 

 in stems generally, and in seeds. The surplus over what the plant needs for 

 its existence, forms what animals consume as food. In some seeds, the starch 

 is further transformed into oil for preservation. Xow neither starch nor oil 

 are direct plant food, but they are stored in the seed for the future use of the 

 germinating plant, as they will keep unchanged, while sugar, the food, will 

 not keep. But when a seed germinates another wonderful change takes 

 place. A fermentive principle is formed, which has the power to transform 

 the oil back into starch, and from starch into glucose, or grape sugar, which 

 can be used directly by the living matter as food, and as material for building 

 up structure, until the green leaves are formed and the roots begin to absorb 

 matter from the soil. 



During the time the seed has been dry, the living matter has simply been 

 dormant, waiting for the coming of water under a proper temperature with 

 the oxygen of the air, to render it once more active. There is a great differ- 

 ence in the length of time during which the living matter will retain its 

 vitality in a dormant state. Some seeds lose their vitality as soon as they be- 

 come completely air dry ; others will retain their vitality for a year, while still 

 others will remain dormant for a number of years, and will grow as soon as 

 the proper conditions of moisture , heat and air are present. Elsewhere will 

 be found a table showing the length of time different seeds are good. 



HOW PLANTS GET FOOD FROM THE SOIL. 



Put several layers of damp blotting paper in a glass jar or tumbler, and 

 on it place several beans, and then cover with a piece of glass, so as to retain 

 moisture. In a few days the beans will germinate, and begin to throw out 

 long white roots. 



Xow examine these roots. You will find that the extreme tip of the 

 rootlet is of rather a conical shape and is smooth and naked, while a little back 

 from the tip a magnifying glass of moderate power will show you that the sur- 

 face of the root is covered with a thick coat of fine velvety hairs. These root 

 hairs are the organs through which the plant absorbs water from the soil. 

 Their extreme fineness precludes the possibility of anything being absorbed 

 that is not in a state of complete solution, as all solid particles must of course, 

 be strained out. The mineral food of the plant is dissolved in the soil water, 

 and is sucked by the root hairs from the watery films that surround each 

 particle of the soil. In order that they shall do this, it is essential that the 



