634 



F A K IVl E R S' REGISTER. 



[No. 11 



and divided in the months of September and Oc- 

 tober, and planted separately to stand the winter, 

 which division produced 67 plants. They were 

 again taken up in March and April, and produced 

 500 plants : the number of ears thus formed from 

 one grain of wheat was 21,109, which gave ihree 

 pecks and thiee quarters of corn that weighed 

 47 lbs. 7 oz., and that were estimated at 576,840 

 grains. 



It is evident from the statements just given, 

 that the change which takes place in the juices of 

 the leaf by the action of the solar light, must tend 

 to increase the proportion of inflammable matter 

 to their other constituent parts. And the leaves of 

 the plants that grow in darkness or in shady places 

 are uniformly pale ; their juices are watery and 

 eaccharine, and they do not afford oils or resinous 

 substances. I shall detail an experiment on this 

 subject. 



I took an equal weight, 400 grains, of the leaves 

 of two plants of endive ; one bright green, which 

 had grown fully exposed to light, and the other 

 almost white, which had been secluded from 

 light by being covered with a box ; alter being 

 both acted upon for some lime by boiling water, 

 in the state of pulp, the undissolved matter was 

 dried, and exposed to the action of warm alcohol. 

 The matter from the green leaves gave it a tinge 

 of olive ; that from the pale leaves did not alter its 

 color. Scarcely any solid matter was produced 

 by evaporation of the alcohol that had been di- 

 gested on the pale leaves : whereas, by the eva- 

 poration of that I'rom the green leaves a consider- 

 able residuum was obtained ; five grains of which 

 were separated from the vessel in which the eva- 

 poration was carried on ; they burnt with flame, 

 and appeared partly matter analogous to resin : 

 53 grains of woody fibre were obtained from the 

 green leaves, and only 31 from the pale leaves. 



It has been mentioned in the third lecture, that 

 the sap probably, in common cases, descends 

 from the leaves into the bark ; the bark is usually 

 60 loose in its texture, that the atmosphere may 

 possibly act upon it in the cortical layers ; but the 

 changes taking place in the leaves appear suffici- 

 ent to explain the difference between the products 

 obtained from the bark and from the alburnum ; 

 the first of which contains more carbonaceous 

 matter than the last. 



When the similarity of the elements of different 

 vegetable products is considered according to the 

 views given in the third lecture, it is easy to con- 

 ceive how the different organized parts maybe 

 formed from the same sap, according to the man- 

 ner in which it is acted on by heat, lisht, and air. 

 By the abstraction of oxygen, the different inflam- 

 mable products, fixed and volatile oils, resins, cam- 

 phor, woody fibre, &c., may be produced from 

 saccharine or mucilaginous fluids ; and by the ab- 

 etraction of carbon and hydrogen, starch, sugar, 

 the different vegetable acids and substances solu- 

 ble in water, may be formed with highly combus- 

 tible and insoluble substances. Even the limpid 

 volatile oils which convey the fragrance of the 

 flower, consist of different proportions of the same 

 essential elements as the dense woody fibre ; and 

 both are formed by different changes in the same 

 organs, from the same materials, and at the same 

 time. 



M. Vauquelin has lately attempted to estimate 

 tlie chemical changes taking place in vegetation, 



by analyzing some of the organized parts of the 

 horse-chestnut in their different stages of growth. 

 He found in the buds collected, March 7, 1812; 

 tanning principle, and albuminous matter capable 

 of being obtained separately, but, when obtained, 

 combining with each other. In the scales sur- 

 rounding the buds, he found the tanning princi- 

 ple, a little saccharine matter, resin, and a fixed 

 oil. In the leaves fully developed, he discovered 

 the same principles as in the buds ; and in addi- 

 tion, a peculiar green resinous matter. The pe- 

 tals of the flower yielded a yellowish resin, sac- 

 charine matter, albuminous matter, and a little 

 wax : the stamina afforded sugar, resin, and 

 tannin. 



The young chestnuts examined immediately af- 

 ter their formation, afforded a large quantity of a 

 matter which appeared to be a combination of al- 

 buminous matter and tannin. All the parts of the 

 plant afforded saline combinations of the acetic 

 and phosphoric acids. 



M. Vauquelin could not obtain a sufficient 

 quantity of the sap of the horse-chestnut for ex- 

 amination, a circumstance much to be regretted ; 

 and he has not stated the relative quantities of 

 the different substances in the buds, leaves, flow- 

 ers, and seeds. It is probable, however, from his 

 unfinished details, that the quantity of resinoua 

 matter is increased in the leaf, and that the white 

 fibrous pulp of the chestnut is formed by the mu- 

 tual action of albuminous and astringent matter, 

 which probably are supplied by different cells or 

 vessels. I have already mentioned that the cam- 

 bmm, from which the new parts in the trunk and 

 branches appear to be formed, probably owes its 

 power of consolidation to the mixture of two dif- 

 ferent kinds of sap , one of which flows upwards 

 from the roots, and the other of which probably 

 descends from the leaves. I attempted, in May, 

 1804, at the time the cambium was forming in the 

 oak, to ascertain the nature of the action of the 

 sap of the alburnum upon the juices of the bark. 

 By perforating the alburnum in a young oak, and 

 applying an exhausting syringe to the aperture, I 

 easily drew out a small quantity of sap. I could 

 not, however, in the same way obtain sap from 

 the bark. I was obliged to recur to the solution of 

 its principles in water, by inflising a small quan- 

 tity of fresh bark in warm water ; the liquid ob- 

 tained in this way was highly colored and astrin- 

 gent; and produced an immediate precipitate in 

 the alburnous sap, the taste of which was sweet- 

 ish, and slightly astringent, and which was color- 

 less. 



The increase of trees and plants must depend 

 upon the quantity of sap which passes into their 

 organs; upon the quality of this sap; and on its 

 modification by the principles of the atmosphere. 

 Water, as it is the vehicle of the nourishment of 

 the plant, is the substance principally given off by 

 the leaves. Dr. Hales found that a sunflower, in 

 one day of twelve hours, transpired by its leaves 

 one pound fourteen ounces of water, all of which 

 must have been imbibed by ile roots. 



The powers which cause the ascent of the sap 

 have been slightly touched upon in the second 

 and third lectures. The roots imbibe fluids from 

 the soil by capillary attraction ; but this power 

 alone is insufficient to account for the rapid eleva- 

 tion of the sap into the leaves. This is fully 

 proved by the following fact, detailed by Dr. 



