550 



FARaiERS' REGISTER. 



[No. 9 



From the (British; Quarterly Journal of Agriculture. 



ON THE EXCRETION FROM THE ROOTS OF 

 PLANTS. 



Sy Mr. Towers. 



It may appear superfluous to recur to the sub- 

 ject of secretion and exudation from the roots of 

 plants ; but as numbers seem to doubt, and obser- 

 vation and experiment are regarded as htt'.e better 

 than theoretic hallucinations. I feel it riirht to enter 

 the lists once more. M. De Candolle founded his 

 hypothesis upon philosophical deduction ; IVI. Ma- 

 caire experimenteti and tested chemically; I rea- 

 soned from observation, and still believe I was the 

 first who, in our own country, placed the theory 

 before the public grounded upon the evidence of 

 comparative observations. I, in 1829, knew nothing 

 of the hypothesis of Geneva, and had met with no 

 Observations upon the phenomena; but I listened 

 to the remarks of practical men, of gardeners, cot- 

 tagers, and intelligent domestic cultivators. I ob- 

 served lor myscli; and, without looking into the 

 laboratory, or applying any non-natural test or 

 re-agent, arrived at and stated those opinions 

 which I published in the " Gardener's Manual." 

 So m.uch I may be permitted to say, in answer to 

 those objections which have been made in refer- 

 ence to the operations of the laboratory. Prospec- 

 tively, I shall observe once for all, that, much as I 

 prize experimental chemistry, 1 witness and read 

 of so many factitious results, when subjects endued 

 with a vital princ'ple are acted upon by chemical 

 powers, that I have desisted, and mean to desist, 

 from any attempts to derive irrefragable evidence 

 from chemical tests, and now base my opinions 

 solely upon the facts resulting from observations of 

 veffetable phenomena. 



That excretions really arc made, there appears 

 to be no rational ground to doubt : no one, 1 think, 

 can go through a course of gardening operations, 

 without becomint; assured that the soil in the field, 

 the garden, and in pots, containing plants, be- 

 comes replete, sometimes to saturation, with spe- 

 cific products. I may mention one (act which has 

 just occurred. I observed that the roots of a 

 young plant of TrnpcBolum atropurpvremn, Lord 

 Auckland's dark-colored nasturtium, had protruded 

 from the hole in the bottom of the pot. The size 

 of this pot is what we here style a 48 ; it measures 

 about four inches internal diameter. On striking 

 out the ball, I was astonished to perceive the ex- 

 tremely povvrerfu! odor which was emitted. The 

 roots had completely worked themselves around 

 the pot, the fibres were matted, but the whole mass 

 was punjrent, as if a quantity of water-cresses had 

 been bruised and applied to the nose. In potting, 

 a great variety indeed of peculiar odors are dis- 

 cernible. Heliotropes yield a powerful and almost 

 animal scent; all \he Jtisticias a stale and ibetid 

 veo;etable elHuvia ; coflee, one of rather a legumi- 

 nous character; but that of the Trapcenlimi was 

 peculiarly punccent. I could enumerate a great 

 many potted plants which yield very distinct odors 

 from the ball of roots, that are quite undiscernible 

 till the plants are removed from the pots; but I 

 desist, as the experiments may be tried by every 

 one. 



I wish, in this place, to meet an objection which 

 may be started against the evidence of odors ad- 

 duced above ; it is this. We admit, many may 



say, that soils about the roots of plants, whether 

 they be confined to po's, or free in the open plots 

 of the garden, emit peculiar odors ; but do not 

 these arise from the roots themselves, and not from 

 matters exuded by them, and dispersed among the 

 particles of the soil ? I am prepared to grant that 

 the roots, as well as the flowers of a vegetable, 

 may possess specific aromas, but these cannot be 

 ditl'used unless they be first emitted ; the fact of 

 diffusion, and that to an extent wdiich renders 

 them perceptible at the distance of many inches, 

 or even feet, is demonstrative of the hypothesis of 

 exudation — that which is disseminated must be 

 .first given forth: this admits of neither hesitation 

 nor doubt. 



If, then, the ground be embued with odorous mat- 

 ter transmitted by the porous s\-stem of the roots; 

 or if it be admitted, that the odors arise from the 

 very substance itself ol millions- of fibres, broken 

 off, and retained by the soil, which cannot by any 

 art be separated from it, the argument is still one 

 and the same; for it is a matter of pure indiffer- 

 ence (provided the ground become saturated with 

 any specific substance) wlielher that substance be 

 gaseous or solid, whether it have been transmitted 

 fi'om the plant, or produced by admixture with 

 broken and lacerated portions of the vegetable 

 body itself. Not to weary the reader with argu- 

 ments upon a subject which must be self-evident, 

 I shall close my present remarks by observing, 

 that I build my hypothesis much more upon the 

 phenomena of vegetable life and growth, that is, 

 upon natural facts, than upon the results of chemi- 

 cal experiments ; and I shall shortly adduce a very 

 closely pursued experiment of a compound nature, 

 in order to establish the fact, that chemical agency 

 ought not to be employed with substances endowed 

 "with the vital principle, and that the inferences de- 

 duced from experiments upon living vegetables 

 placed in unnatural situations are frequently found- 

 ed in, and lead to error. Dead matter, mineral 

 substances, and the like, are the proper subjects 

 tor chemical analysis; upon them ils power can 

 be legitimately brought to bear. The living being 

 is embued with powers peculiar to itself; it is sub- 

 jected to laws tliat govern its mode of existence; 

 all its phenomena are indeed dependent upon a 

 specific vita! energy : hence we cannot with safety 

 attempt to arrive at definite conclusions from the 

 operation of agents which interfere with and de- 

 stroy that energy. M. ISlacaire's experiments are 

 conclusive as far as they go ; his ingenuity, and 

 the zeal with which he followed up its dictates, 

 are highly to be ap|;lauded ; but the experiments 

 which I above alluded to, will, I doubt not. afford 

 proof, that nature must be investigated in her oinii 

 luay, and that he who assails, instead of consulting 

 her, will of necessity become embarrassed by per- 

 plexing and contradictory results. 



That which led me, in the summer of 1834, to 

 undertake my very protracted experiment, was 

 the assertion frequently met with, that the sap- 

 vessels of pla)ifs had been, and might be again, made 

 manifest by the agency of chemical tests. 1 had 

 long doubted the correctness of this assertion, and 

 therefore determined to briuii the matter to imme- 

 diate issue. Conceiving that the balsam (Balsa- 

 mina hortcnsis) presented the readiest means to 

 effect my purpose, because of its rapid growth, 

 juiciness, and grealtransparency of stem, I selected 

 three cuttings from a plant of nearly the same size ; 



