1838] 



FARMERS' REGISTER, 



641 



tion of this gas, and in this condition enters the 

 ground. No sooner does it come in contact, with 

 the seed in the first instance and with the root af- 

 terwards, than it is absorbed and iis materials used 

 for increasinjr the size of the vegetable structure. 

 When the portion of air above the spot, has in 

 this way been exhausted ol" carbonic acid, a sup- 

 ply is obtained from the neigliboring portions, in 

 consequence of that strong tendency which gases 

 manilest, to intermix and diffuse themselves 

 throughout each other. This process is repeated 

 againand again, and thus the clover increases in 

 size. Perhaps some one may ask, from whence 

 is this gas obtained in the first place? From 

 many sources, but principally from decaying ve- 

 getables, such as are found in the woods and 

 along the fence sides. The quantity of the seve- 

 ral elements which enter into the composition of 

 our globe, is fixed; it is impossible for man either 

 to increase or diminish this quantity, and it is 

 equally impossible for him to convert one of these 

 elements into another. All he can do is to make 

 an economical use of that vvhich already exists, to 

 gather up those portions which subserve no valua- 

 ble ends, and apply them to use. This is what 

 the farmer does in sowing hie land with clover. 

 He impresses the very wind into his service, for 

 every wind that sweeps over a field of clover, 

 laden as that wind is with the materials of vege- 

 table structures, is made to contribute to its growth. 

 After a large portion of vegetable matter has, in 

 this way, been collected upon the once barren 

 spot, it is ploughed under and secured for future 

 use. 



Again ; in absorbing nourishment from the 

 earth, the roots of a plant do not seem to exercise 

 any choice; but drink up every thing, presented 

 to them in a sufficiently fluid state. This we learn 

 from actual experiment. Almost any substance 

 which is soluble in water, may be made to enter 

 vegetable systems. After a heterogeneous mass 

 is thus taken up by a plant, such portions as are 

 suited to its nourishment are retained, whilst such 

 as are not suited, are returned to the roots, and by 

 them again deposited in the soil. From observa- 

 tion, we learn that the matter thus rejected, is 

 thrown back in such a state as to be not only un- 

 Buitable to the nourishment of the plant (rejecting 

 it) but positively deleterious. It has also been 

 ascertained, that the substances rejected by diffe- 

 rent plants differ from each other; and this to such 

 an extent that the matter rejected by one plant, is 

 well adapted to the nourishment of another. 

 With a knowledge of these facts, we can assign 

 the reason, why it is not a good plan to sow the 

 same crop upon the same pieces of land for seve- 

 ral years in succession. It will not do to say (as 

 is often done) that a second crop of wheat will 

 not grow as well upon the same spot, as the first, 

 because that spot has been so much exhausted by 

 the first. This is, it is true, one reason; but if it 

 be the only reason, or even the principal reason, 

 why is it that a crop of corn succeeds so well? 

 The failure in the second crop of wheat, arises 

 not so much from the exhaustion of the soil, as 

 from that soil's containing a portion of matter po- 

 sitively deleterious to the growth of wheat, and 

 which was deposited by the first crop. At the 

 same time this matter is not injurious to the crrowth 

 of corn, and hence the crop of corn is almost as 

 good as it would have been, had wheat never been 



sown upon the land. If we could aecertnin the 



precise character of the matter which ia retained, 

 and of that vvhich is rejected, by each of the several 

 crops conmionly cultivated, it would be an easy 

 niatter lo determine the best order in which cropa 

 can succeed each other. Perhaps too, if this sub- 

 ject was better understood, we should find that 

 the way in vvhich some manures benefit crops, is 

 not by supplying nutritious matter to them, but 

 by removintr this deleterious matter from their 

 roots. If this matter possess the character of an 

 acid, as it is more than probable it does in some 

 cases, lime would act in this way. Being a sale- 

 fiable base, it would unite with the acid and neu- 

 tralize its properties. 



I might go on and multiply instances such as 

 these, did the occasion call for it: but as my ob- 

 ject is, not to give a lecture on vegetable physio- 

 logy; but by illustrating its application to agricul- 

 ture, to show its importance lo the farmer, these 

 will suffice. Perhaps some one may ask, if sci- 

 entific principles are nothing more than facts, ar- 

 raged and generalized, why is it, that knowledge 

 in this form, is more valuable, than in the form of 

 unconnected observations; the form in which this 

 knowledge is at first obtained? 



There are several reasons. Knowledge in the 

 form of science is more easily retained, and is 

 more perfectly at the command of the possessor, 

 than it can possibly be, in the form of unconnect- 

 ed observations. I doubt not that the experience 

 of every one here will confirm the statement, that 

 it is easier to remember fifty effects, when we can 

 trace them to one common cause, than it is to re- 

 member five, when we can trace them to no cause, 

 A knowledge of the cause of any number of ef- 

 fects, serves as a band, by which they are bound 

 in one common bundle, and thus secured from be- 

 ing scattered and lost. It is one of the character- 

 istics of science, that the relation between cause 

 and elTect is distinctly traced out. 



Another reason why it is desirable to have our 

 knowledge in the form of science is, that in this 

 form it will serve to direct us in our course of ex- 

 periment and observation. Such is the constitu- 

 tion of nature, so intimately are the various parts 

 of creation interwoven, that a cause generally 

 gives rise to several efl^ects. When we have traced 

 an observed effect back to its cause, we can gene- 

 rally infer other effects, vvhich will spring from the 

 same cause; and these often of a character en- 

 tirely different from the one first observed. To 

 illustrate my meaning by an instance. In attempt- 

 ing to sink a pump to an uncommon depth, it was 

 found that the water could not be raised by it, to 

 a height greater than 32 feet. The cause of the 

 rise of the water was ascertained to be the weight 

 of the atmosphere. The reason why the water 

 would not rise to a height greater than 32 feet, 

 was that the weight of a column of our atmo- 

 sphere was only equal to that of a column of wa- 

 ter of the same diameter, and 32 feet high. It 

 was at once inferred, that as the weight of the at- 

 mosphere was fixed, it must sustain columns of 

 different liquids at heights, inversely proportioned 

 to their specific gravities. And again; that as we 

 rose from the level of the sea, leaving as we 

 must, a part of this atmosphere behind us, the 

 height at which a column of any liquid would be 

 sustained, must diminish in proportion to our rise. 

 Thus by tracing the refusal of a pump to act in 



