THE IRRIGATION AGE. 



47 



and semi-arid regions to plow the grain in "dry" in 

 the summer or dry months, and when the rains come in 

 the autumn, or say, in November and December, the 

 grain sprouts in a few days. 



The reason why light is prejudicial to germination 

 and why atmospheric air is necessary is because during 

 germination seeds absorb oxygen gas and give off car- 

 bonic acid, and they can not sprout unless oxygen gas 

 is within their reach, the only place where they can 

 obtain it being from the atmosphere. In the sunshine 

 the leaves of plants give off oxygen gas and absorb 

 carbonic acid, while in the dark the reverse takes place. 

 Hence, if seeds are exposed to the sunlight, they give 

 up oxygen which they need and absorb carbonic acid 

 which kills them. 



5. During germination, acetic acid (vinegar) and 

 diastase are produced, as mentioned in the last pre- 

 ceding chapter, whereby the insoluble starch is con- 

 verted into sugar, which is soluble and can be absorbed 

 as food by the youthful plant. 



6. The tender young shoot which ascends from 

 the seed consists of a mass of organs or vessels, which 

 gradually increase in length, sometimes "unroll" into 

 the first true leaves. The vessels of this first shoot do 

 not consist of unmixed woody fiber, that is not formed 

 until after the first leaves are fully developed. In the 

 meantime the young root is making its way down into 

 the soil seeking a storehouse of nourishment upon 

 which it can draw when the sugar of the seed shall 

 all have been consumed. 



These phenomena are brought about in the follow- 

 ing manner: The seed absorbs oxygen and gives off 

 carbonic acid. This transforms a portion of the starch 

 into acetic acid, which aids the diastase to transform the 

 insoluble starch into soluble sugar, or food that can be 

 taken up into the plant. It also dissolves the lime in 

 the soil contiguous to it, and returns into the plant, 

 carrying the lime or other dissolved earthy substances 

 with it. The seed imbibes moisture from the soil, and 

 this dissolves the "sugary starch," so to speak, and it 

 all goes into the circulation, and the plant is enabled to 

 grow and develop its first leaves. It is like a baby fed 

 on milk. 



When the true leaves have expanded, woody fiber 

 begins to make its appearance, which can be readily 

 understood by attempting to break the plant stalk, a 

 thing easily done before the first leaves appear, but not 

 so easily afterward. The sugar in the sap is now con- 

 verted into woody fiber, the root drawing up food from 

 the soil, and the leaf drinking oxygen and carbonic acid 

 from the atmosphere. The moisture must still be con- 

 stant, for the root can not absorb food unless the latter 

 is properly dissolved. 



FROM THE FIRST LEAVES TO THE FLOWER. 



The plant now enters upon a new stage of exist- 

 ence, deriving its sustenance from the air and the soil. 

 The roots descend and the stem shoots up, and while 

 they consist essentially of the same chemical substances 

 as before, they are no longer formed at the expense of 

 the starch in the seed, and the chemical changes of 

 which they are the result are entirely different. 



Here is where the farmer will make a fatal mistake 

 if he relaxes his vigilance. The whole energy of the 

 plant is directed toward one single goal, that of pre- 

 paring for the flower which is the forerunner of the 

 fruit. What the flower is, that will be the fruit. 



The leaf absorbs carbonic acid in the sunshine and 



gives off oxygen in equal bulk, and the growth of the 

 plant is intimately connected with this absorption of 

 carbonic acid, because it is in the light of the sun that 

 plants increase in size. Now, by this function of the 

 leaf, carbon is added to the plant, but it is added in the 

 presence of the water of the sap and is thus enabled by 

 uniting with it to form any one of those numerous 

 compounds which may be represented by carbon and 

 water, and of which, as was shown in the last chapter, 

 the solid parts of plants are principally made up. This 

 period may be called the period of "plant building," 

 the plant utilizing every material that will bring it up 

 to the condition of flowering. 



The sap flows upward from the roots, through 

 which have been received the silica, potash, soda, phos- 

 phorous, etc., in solution, and reaching the leaves, meets 

 the carbonic acid flowing in through the myriad of 

 mouths in the leaves, and then flows along back down- 

 ward to the roots, depositing, as it descends, the starch, 

 woody fiber, etc., which have been formed by the action 

 of the carbonic acid. Thus the sap circulates round and 

 round like the circulation of blood in the veins of an 

 animal, except that its heart is not a central organ, but 

 an attraction of affinities among the substances which 

 enter into plant life, affinities constantly pursuing each 

 other through the veins or capillaries of the plant, and 

 forming unions, the products of which add to the 

 growth of the plant and enable it to accomplish its des- 

 tiny. 



During this ante-flowering period there are pro- 

 duced in the plant not only woody fiber, but other 

 compounds which play an important part in a subse- 

 quent stage of its existence ; one of these, the most im- 

 portant, is oxalic acid, which has already been alluded 

 to. This acid seems to be formed at this period to aid 

 in perfecting the future fruits that will follow the 

 flower. What is curious about these various acids now 

 formed is that many of the plants are sour in the 

 morning, tasteless during the middle of the day, and 

 bitter in the evening. The reason is, during the day 

 these plants have been accumulating oxygen from the 

 atmosphere to form acids, but as the day advances this 

 oxygen is given off, carbonic acid is imbibed and the 

 acids decomposed. Hence the sourness disappears, but 

 the materials are in the plant ready for use when re- 

 quired the acid storehouse is filling against the day 

 of need. 



In the case of wheat, barley and other grains, the 

 chief energy of the plant, previous to flowering, is ex- 

 pended in the production of the woody fiber of its stem 

 or stalk, and growing branches, drawing up from the 

 soil for that purpose the various ingredients they re- 

 quire from among the inorganic elements, which unite 

 with the vegetable acids in the sap and form compounds 

 which are essential to the perfection of the grain or 

 seed. In the first stage of its growth the starch of the 

 seed is transformed into gum, and then sugar; in its 

 second stage, when the leaves are expanded, the starch 

 is transformed into woody fiber. 



FROM THE FLOWER TO THE RIPENING OF THE FRUIT. 



The sap has now become sweet and milky, indi- 

 cating sugar and starch. These during the third period 

 are gradually transformed in the sap into starch, a 

 process exactly the reverse, or contrary of that in the 

 first and second periods. The opening of the flower 

 from the swollen bud is the first step taken by the plant 

 to produce the seed by which its species is to be per- 



