48 



THE IERIQATION AGE. 



petuated. At this period a new series of chemical 

 changes commence in the plant. 



1. The flower leaves absorb oxygen and emit car- 

 bonic acid all the time, both by day and by night. 



2. They also emit pure nitrogen gas. 



3. The juices of the plant cease to be sweet, even 

 in the maple, sugar cane, and beet; the sugar becomes 

 less abundant when the plant has begun to blossom. A 

 change not difficult to understand when it is considered 

 that nature is at work preparing to perfect the seed or 

 fruit, and is not working for commercial interests. 

 The structure of the plant is now of no consequence, 

 and ceases to be of any importance. The imbibing of 

 oxygen, which is the parent of all acids, is intended to 

 convert the sugar into material for the seed, or fruit, 

 the wheat or the peach, the strawberry or the squash. 



The husk of grain bearing grasses, corn, wheat, 

 oats, etc., is filled at first with a milky fluid which be- 

 comes gradually sweeter and more dense, or thicker, 

 and finally consolidates into a mixture of starch and 

 gluten, such as may be extracted from the grain as has 

 already been said. 



The fleshy envelopes of many plants, at first, taste- 

 less, become sour and finally sweet, except in the lime, 

 lemon and tamarind, in which the acid remains sensible 

 to the taste when the seed has become perfectly ripe. 



Fruits, when green, act upon the air like green 

 leaves and twigs, that is, they imbibe oxygen and give 

 off carbonic acid, but as they approach maturity they 

 also absorb or retain oxygen gas. The same absorption 

 of oxygen takes place when unripe fruits are plucked 

 and left to ripen in the air, as is common in the case 

 of tomatoes, oranges, lemons, and bananas. After a 

 time, however, they begin throwing oil carbonic acid 

 and then they ferment, spoil or rot. 



RIPENING OF THE FRUIT. 



In the case of pulpy fruits, such as the grape, 

 lemon, orange, apple, peach, plum, etc., when unripe 

 and tasteless, they consist of the same substances as the 

 leaf, a woody fiber filled with tasteless sap, and tinged 

 with the green coloring matter of the plant. For a 

 time, the young fruit performs the functions of the leaf, 

 that is, it absorbs carbonic acid and gives off oxygen, 

 thus extracting from the atmosphere a portion of the 

 food by which its growth is promoted and its size is 

 gradually increased. Remember what has been hereto- 

 fore said about carbon constituting the bulk of the 

 plant. 



By and by, however, the fruit becomes sour to the 

 taste, and this sourness rapidly increases, while at the 

 same time it gives less oxygen than before, the retain- 

 ing of the oxygen being, as has been said, the cause of 

 the sourness, the oxygen converting the sugar into tar- 

 taric acid aud water. The grape is an illustration, 

 though the same thing happens in fruits abounding in 

 the other vegetable acids. 



This formation of acid proceeds for a certain time, 

 the fruit becoming sourer and sourer. Then the sharp 

 sourness begins to diminish, sugar is formed, and the 

 fruit ripens. The acid, however, rarely disappears en- 

 tirely, even in the sweetest fruits, until they begin to 

 decay. 



During the ripening of the fruit, the woody or 

 cellular fiber gradually diminishes and is converted into 

 sugar. This will be noticed in several kinds of fruits, 

 particularly winter pears, which are uneatable when 

 actually ripened on the tree, but become ripe, long after 



plucking, by continuing to absorb oxygen, which con- 

 verts the woody fiber, or cellular tissue, into sugar, 

 which is not difficult to understand, as woody fiber is 

 very similar to sugar in its chemical constitution. 



It should be noted that the entire forces of the 

 plant are concentrated upon the seed, the element, or 

 agent of reproduction, the pulp of the most delicious 

 fruit, the kernel of the sweetest nut being nothing but 

 protective envelopes and food supplies for the germ 

 when the time and opportunity shall arrive for germi- 

 nation. So that the object of the plant in making so 

 many transformations is not fruit, but seed. 



FROM THE FALL OF THE LEAF TO THE FOLLOWING 

 SPRING. 



When the seed is fully ripe the functions of annual 

 plants are ended. There is no longer any necessity for 

 absorbing and decomposing carbonic acid; the leaves, 

 therefore, begin to take in only oxygen, with the result 

 that they are burned up, so to speak, and they become 

 yellow, or parti-colored; the roots decline to take in 

 any more food from the soil, and the whole plant pre- 

 pares for its death and its burial in the soil by becoming 

 resolved into the organic and inorganic elements from 

 which it sprang, and of which it was originally com- 

 pounded. 



But of trees and perennial plants, a further labor 

 is required. The ripened seed having been disposed of, 

 there are incipient young buds to be provided for, buds 

 which are to shoot out from the stem and branches on 

 the ensuing spring. These buds are so many young 

 plants for which a store of food must be laid away in 

 the inner bark of the tree, or in the wood of the shrub 

 itself. 



The sap continues to flow rapidly until the leaves 

 wither and fall, and then the food of the plant is con- 

 verted partly into woody fiber and partly into starch. 

 It has been shown how these substances are converted 

 into food by chemical changes, or transformations, and 

 these changes do not cease so long as the sap continues 

 to move. Even in the depth of winter the sap slowly 

 and secretly stores up starchy matter, in readiness, like 

 the starch in the seed, to furnish food to the young 

 buds when they shall awaken in the spring from their 

 winter sleep. It is the same process as in the case of a 

 seed planted in the ground. 



RAPIDITY OF GROWTH. 



It has been shown that from carbonic acid and 

 water, the plant can extract all the elements of which 

 its most bulky parts consist, and can build them up in 

 numerous ways. But the rapidity with which the plant 

 can perform this building up is almost incredible. 



Wheat will shoot up several inches in three days, 

 barley six inches in that time, and a vine twig will 

 grow about two feet in three days. Cucumbers have 

 been known to attain a length of twenty-four inches in 

 six days, and a bamboo has increased its height nine 

 feet in less than thirty days. 



The rapid growth of vegetation in semi-tropical 

 arid and semi-arid regions is phenomenal. A young 

 eucalyptus tree has been known to grow thirty feet in 

 a single season, and wheat or barley three inches high 

 three days after planting is not uncommon. Potatoes 

 (solanum tuberosum) have run up to fifteen pounds in 

 weight before the plant had time to blossom, in fact, it 

 never did blossom. 



(To Be Continued.) 



