226 



FARMERS' REGISTER— GAM A GRASS. 



lodging upon it, and especially by cutting close to 

 the main branch or stem. The main object is to 

 procure a rapid developement of the new wood, in 

 order that the exposed surface may be secured as 

 speedily as possible from the action of air and 

 moisture ; and this, we believe, is best obtained 

 by reducing the cut as nearly as possil)le to tlie 

 condition of a vertical wound on the stem. All 

 pruning, then, should be avoided as much as pos- 

 sible; but where it is absolutely necessary, it 

 should be performed as soon and as completely 

 as the young plant or branch may bear it with 

 safety. 



The action of poisons on vegetable structure. 



The action of poisons on vegetables is analagous 

 to that which they produce on animals. One class 

 is corrosive, and destroys the tissue on which it 

 acts ; whilst another class is narcotic, and destroys 

 A'itality without producing any decided alteration 

 on the tissue itself It has been ascertained that 

 nearly all substances which are poisonous to ani- 

 mals, are likev/ise so to vegetables, though the in- 

 tensities of their several actions are different in the 

 two kingdoms; but, besides these, there are many 

 substances innoxious to animals, which are de- 

 structive to vegetable life. In fact, it should seem 

 that almost every thing that vegetables can im- 

 bibe is injurious to them, excepting Avater, the in- 

 sipid earthy salts, carbonic acid, and other gases, 

 gums, and mucilaginous substances, and finally, 

 certain animal matters when introduced in very 

 weak solution. It has been supposed that the pre- 

 sence of a nervous system might be assumed 

 to exist in vegetables, from the mode in which 

 they are destroyed by narcotic poisons ; hut there 

 is this remarkable difTerence in the mode in which 

 these substances act on animn:ls and on vegetables : 

 on the former they act by " sympathy" upon cer- 

 tain parts with which they have no immediate con- 

 tact, whilst ill the latter they produce their effect 

 only on those parts of the tissue into which they 

 are introduced. In vegetables, also, all poisons 

 exert their action upon the cellular tissue, whilst 

 in the more complicated structure of the animal 

 frame different poisons will attack only particular 

 tissues ; which again seems to prove the existence 

 of no more than one single faculty in vegetable 

 life, as we concluded to be the case, from other 

 considerations, in the beginning of this article. It 

 is a curious fact in the action of vegetable poisons, 

 that a plant may be killed by the poison which it 

 has itself secreted, as a viper may be stung to 

 death by its own venom. Hence it has been very 

 generally noticed, that the soil in which any parti- 

 cular plant has grown, and into which it has con- 

 sequently discharged the excretions of its roots, is 

 rendered noxious to the growth of plants of the 

 same or of allied species, though it be quite adapt- 

 ed to the support of other species. This fact is of 

 the greatest importance in an economical point of 

 view, as the whole theory of the rotation of crops 

 may be considered to depend upon it. The disco- 

 very of this important step in agriculture Avas 

 probably made by the Belgians; at least they have 

 the merit of having developed the theory of it. — 

 Formerly it used to be said, that the whole secret 

 of good husbandry consisted in ploughing well, 

 and in manuring well ; but to these must now be 

 added the equally important art of so arranging the 

 cultivation of dirt'erent crops that they may mutu- 



ally assist each other, and thus enable the farmer 

 to obtain the greatest possible annual return from 

 the same land. The whole theory depends upon 

 the fact, that all plants succeed badly upon lands 

 w]u"ch have lately borne crops of the same species 

 as themselves, or even of the same genus, or of 

 the same family. This effect is not owing to any 

 exhaustion of the soil that must have taken place 

 during the groAvthof the previous crop, but arises 

 from a corruption of the soil, by the intermixture 

 of vegetable excretions given out at the root, 

 which excretions are always more deleterious to 

 plants of the same kind than to others. It is even 

 ascertained that the excretions of some plants are 

 beneficial to the growth of others of a different fa- 

 mily ; the LeguminoscB, for example, improving 

 the soil for the GraminecB. Agriculturists have 

 proposed various theories to account for the bene- 

 ficial results obtained by a rotation of crops. Some 

 have supposed that one species, by its denser fo- 

 liage, chokes the weeds which otherwise would 

 spring up, and assists the crop in exhausting the 

 soil ; others have attributed the improvement that 

 has taken place to the remains of the previous 

 crop, which they suppose may have acted as ma- 

 nure ; a third have said, that the roots of different 

 crops extend themselves to different depths, and so 

 extract their nourishment from portions of the soil 

 which do not interfere with each other; and last- 

 ly, it has been urged that plants of different fami- 

 lies may possibly derive their nourishment from 

 different materials. It may be true tliat some of 

 these causes have a certain degree of influence in 

 determining which may be the most proper plants 

 for a rotation, but they can only be considered as 

 of very secondary importance when compared 

 with that Avhich relates to the deterioration of the 

 soil, by its intermixture with the radical excre- 

 tions of a previous crop. After enumerating some 

 of the collateral circumstances which should direct 

 thejudgment of cultivators in selecting such plants 

 as may be best adapted to a rotation of crops in 

 any particular district, De Candolle proposes the 

 following fundamental and physiological princi- 

 ples, which ought to be attended to where com- 

 plete success is to be expected. F'irst,a new crop 

 ought never to succeed another of the same kind, 

 unless under some very peculiar circumstances, 

 as where the soil is annually renewed, or where it 

 is naturally so fertile as to be capable of resisting 

 the inconveniences which ordinarily result from 

 such a system. Secondly, a new crop ought not 

 to succeed another which has been raised from 

 plants of the same fiimily. A remarkable excep- 

 tion to this rule occurs in the practice adopted in 

 tlie valley of the Garonne, where the soil admits 

 of a biennial alternation between wheat and maize. 

 Thirdly, all plants Avith acrid and milky juices in- 

 jure the quality of the soil, and their remains 

 should never be buried after the removal of a crop. 

 Fourthly, plants with SAveet and mucilaginous 

 juices improve the soil for others of a different fa- 

 mily. The chief of these are the LeguminoscB, 

 Avhich are commonly adopted in practice for this 

 purpose. 



Gania G'rass. 



From the Newbern Spectator. 

 The grass which passes under this name has ac- 

 quired a considerable degree of celebrity, and pro- 

 mises to become of much importance to the agri- 



