1856. 



NEW ENGLAND FARMER. 



267 



botanists, its mucilage or albumen ; around this is 

 laid up in most seeds a quantity of starch, a sub- 

 stance readily changeable into gum, and then into 

 suo'ar, by the action of the albumen, which forms, 

 by chemical changes, the principle called diostase. 

 In other plants an amjgdalaceous substance takes 

 the place of starch, and undergoes peculiar chemi- 

 cal changes in the process of germination. In the 

 bean pea and in cucurbitaceous plants, such as the 

 pumpkin, squash, cucumber and melon, it changes 

 into organized cotyledonous leaves, as it pushes 

 from the soil and meets the light. In cereal grains 

 ■we have the mucilage in the chit, then the layer of 

 starch mingled with cellulose, and around this a 

 hard substance called gluten, containing a fixed oil 

 in cells. This is more obseiTable in the grain of 

 Indian corn. This gluten, which is the last of the 

 ingredients to decompose in the soil, furnishes am- 

 moniacal products. The starch forms first gum 

 and then grape sugar. The phosphates are all con- 

 tained close around the germ in the chit or muci- 

 lage. All seeds are formed on similar principles, 

 and there is a grand unity in their plan. 



The seed of the grape is richly supplied with 

 phosphates and with the alkalies, potash chiefly, 

 with some soda. It liears also the organic nutri- 

 ment of the embryo vine. The production of these 

 little seeds, or grape stones, as they are called, is 

 the most elaborate performed by the plant, and 

 during the process, the grape ceases to swell, and 

 becomes almost stationary in its functions of growth, 

 so far as the eye can discover. Its whole ener- 

 gies are bent on perfecting of the seed. This ac- 

 complished, then the grapes undergo a sudden 

 change, and begin what the cultivator calls the sec- 

 ond swell of the fruit, when it becomes full _ of 

 juices, which change by ripening into saccharine 

 and aromatic syrups, tempting the palate of man. 

 If, in out-dooi- growth, there happens to come 

 on a few rainy days, the grapes swell quite large- 

 ly, but are not so sweet as if less liberallv sup- 

 phed with water. Hence, the judicious gardener 

 takes the hint from nature, and wishing to pro- 

 duce more concentrated saccharine, and higher 

 flavored juices, is sparing in his supply of water to 

 the roots ; and if he understands vegetable physi- 

 ology, he is not guilty of the barbarism of plucking 

 off' the leaves from his vines, by which he M'ould in 

 part, at least, defeat the elaboration of the sap, 

 which is forming the sweet juices of the grape. It 

 is an error to remove the leaves under the belief 

 that by so doing more sunhght may come to the 

 bunches of grapes. It is on the leaves the sun- 

 light must fall, to produce the proper elaboration of 

 the sap. Every boy Avho has picked wild grapes 

 in the swamps, knows that only sour grapes are 

 found on branches that have lost their foliage. To 

 pluck off" the leaves from a plant, is analogous to 

 the removal of the lungs of an animal, and the 

 diminution of them is like the destruction of a por- 

 tion of the lungs. 



The circulation of plants was next discussed. By 

 what power does the sap ascend in the stem ? — 

 Is it by capillary attraction ? Is it by attraction of 

 the buds? These were two of the old botanical 

 theories. If by capillary attraction, allo\ving it to 

 be equivalent to the production of a perfect vacuum, 

 it can only raise the sap from 34 to 40 feet, and if it 

 is assumed to be owing to the attraction of the buds, 

 the same objection stands in the way, m., that it 

 will not account for the elevation of a column of 



sap from 100 to 200 feet in our tall trees and high 

 climbing vines. 



The sap must then ascend by a vis a tergo — or 

 rather, a force from below, — and this force we find 

 in the beautiful discovery of M. Dutrocht oi endos- 

 mose, or internal impulse. If we tie a piece of blad- 

 der over the mouth of a small jar or cupping glass, 

 open at the bottom, so as to make a false bottom 

 to the jar by the membrane, and then fill the jar 

 with a syrup of sugar, or any fluid denser than wa- 

 ter, and attach an open tube to the neck of the jar, 

 and then sink the jar to its neck in water, it is ob- 

 vious that there is no diff"erence of pressiu-e between 

 the inside and outside ; still in a quarter of an hour 

 it will be observed that the fluid rises in the tube, 

 and will continue to rise until it overflows at its up- 

 per opening. Now this membraneous bottom is 

 equivalent to the spongiole or the rootlet of the 

 plant. But if we add a series of diaphragms in our 

 tube, instead of obstructing the ascent of the liquid, 

 they will each give it a Hft, and so it will go on as- 

 cending to the highest part. In the stem of a plant 

 are myriads of these crossing diaphragms, and each 

 one of them tends to Hft the sap upwards, while 

 some of the lateral ones direct it to the glandular 

 apparatus of the plant. The evaporation from the 

 leaves continuously inspissates the liquid sap, and it 

 becomes more and more endosmetrical, as it be- 

 comes denser by this process. 



In winter and during the rest of plants, the sap 

 in the roots becomes denser, and is ready with the 

 return of warmth and moisture to absorb water and 

 saline and soluble organic matters from the soil. — 

 When the sap reaches the green buds, they swell 

 and put forth their leaves ; these leaves are acted 

 upon by sunlight in such a manner as to effect the 

 most marvellous chemical changes in the sap ; car- 

 bonic acid gas from the air is greedily absorbed by 

 the leaves, and oxygen gas is exhaled in its place. 

 This carbonic acid gas, the poisonous breath of ani- 

 mal respiration, and the product of combustion of 

 carbonaceous fuel, is changed into the proper juice 

 of the plant, — forms gum, sugar, and many other 

 of the ingredients we find in the fruit. In the chem- 

 ist's laboratory, red hot potassium is required for 

 the reduction of carbon from carbonic acid, but in 

 the finer chemistry of plants, this decomposition is 

 slowly and silently effected, without the dazzling 

 red blaze of the chemist's experiment. Not only is 

 the carbon of wood produced, but also an infinite 

 number of hydorocarbonaceous substances, inimita- 

 ble by the chemist, and organic substances which 

 vegetable life alone can produce, are formed. So 

 rapid is the absorption of carbonic acid gas by fresh 

 and healthy foliage, exposed to full sunlight, that 

 according to Dumas and Cahours, if a branch is in- 

 closed in a glass globe, and a blast of air is driven 

 through it by the bellows, all the carbonic acid is 

 abstracted from the air by the foliage. 



It was formerly supposed that plants produced 

 carbonic acid during the night, and hence the idea 

 of Virgil, that the evening shade is unfavorable to 

 singers was supposed to be justified by this botani- 

 cal view of the matter. But more exact researches 

 have shown that plants do not produce carbonic 

 acid, but only allow that which they absorb from 

 the earth to pass their stomata or breathing pores 

 of their foliage. 



Years ago, while encamped in the unbroken for- 

 ests of Maine, I often reflected upon this physiolog- 

 ical theory of the older botanists and chemists, and 



