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THE TROPICAL AGRICULTURIST, 



[March i, 1B84. 



ital, but which, nevertheless, has special requirements 

 which, uudor the varying iuflueuces of soU, climate 

 and culture, take time and experience to arrange for. 

 1 sincerely hope that tlie investigation of the causes 

 of fungoid visitntiona generally may soon enter upon 

 a new phase aud venture to predict that if the pliysio- 

 logical purposes for whidi lime, phoapliates and 

 alkalis are required in plant-life are carefully deter- 

 mined, it will be found quite as possible to pre- 

 vent certain soluble tiausition pioducts in the leaf- 

 cells being preyed on hy microscupic parasites as to 

 render the stan-hy gloss on Manchester piece-goods 

 proof against an attack of mildew. 



GRAHAM ANDERSON. 



[The extracts to which Mr. Audeisou alludes are given 

 below. When M. Ville's book appeared, we reviewed it 

 fully and made copious extracts, yubsequently Lawes 

 disputed his theory that farmyard manure could be 

 entirely dispensed with. — Ed.] 



{Extracts.) 



MANUKES. 



Effect Consequent on a Want of the Dominant Constituent. 



'* Who does not remember the tenible effects protluced 

 in Irelaiad by the potato disease at the time of its first 

 outbreak ? 1 shall say uothiug of the explanations that 

 have been given of these formidable scouiges. AVhether 

 the parasites are the cause or the effect of the evil, whether 

 they owe their origin to microscopic germs floating in the 

 atmosphere, or result from the evolution of cells oi certain 

 tissues which become indejjendent of the relatively superior 

 organism of which they form a part, and live henceforth a 

 life of their own ; whatever be the explanation that is 

 generally accepted, one certain fact, intiexible in its m.iiii- 

 festations, governs all, viz., that the absence, or, at auy 

 rate, the scarcity of the soil of certain elements indis- 

 pensable to the life of plants, multiply if they do not 

 absolutely give rise to those diseases of which we have 

 just been speaking. For six years, these phenomena at 

 Vinceimes have not changed. Wherever the soil does not 

 receive potash, or where it gets no manure, the plants 

 are poor and stunted with withered and dry black leaves, 

 and that too in the mouth of June, when the other plant- 

 ings are still hi a state of luxuriant growth." 



" Vines are subject to similar effects, and although my 

 experience is less extended in this direction, it enables me 

 to be equally positive. AVhere potash is lacking, the leaves 

 do not attain their full development; in the month of 

 July they become red and spotted with black, after which 

 they become dry and are easily reduced to powder uuder 

 »he pressure of the fingers." — Vjlle. 



" Besides this, the lack of potash ui the soil is coin- 

 cident with the appearance of potato disease, wheuce we 

 may draw a second conclusion that when plants are de- 

 prived of then- dominant mineral constituent, and con- 

 sequently of one of the most essential constituents of their 

 existence, they become the prey of inferior organisms such 

 as microscopic fimgi, aphides, &c. We liave Jiere a start- 

 ling aud unexpected explanation of the cau.se of one of 

 the most terrible plagues with which the farmer has to 

 fight, namely, plant diseases. For many years the same 

 phenomena have been reproduced at Vinceunes with in- 

 variable regularity. Until the end of May, besides the 

 very marked differences in the size of the plants in the 

 (hfferent plots, nothing striking seems to indicate the great 

 change which is on the point of takmg place. The change 

 first manifests itself about the middle of the month of 

 June, and invariably begins with the plot which had re- 

 ceived manure iri which the potash has been suppressed, 

 as well as in that which has received no manure at all. 

 The plants in the plots which have been dressed with 

 normal manure are luxuriantly green, but those in the 

 plot which has received no potash, and in that which 

 has received no manure at all, a number of copper- 

 coloured spots begin to make their appearance aud shortly 

 afterwards begin to spread very rapidly, gradually extend- 

 ing themselves over the whole of the foliage and ilrying 

 up the plant as if a burning wind had passed over it." 



" Until lately, I always thought that the leguminosffi an I 

 the potato were the plants which showed a special pre- 

 ference for potash, but the vine distances them in this 

 respect in a most surprising manner. In the case of tlic 

 potato the suppression of potash manifests itself by adimui- 

 ution of the crop; with the vine, however, little or no 

 fruit makes its appearance, and we virtually get no croj) 

 at all. The vine itself barely sends forth two or three 

 feeble shoots, and the few shriveUed leaves are hardly as 

 large as a crown piece, whilst those of the plants which 

 have been di'essed with normal manure are as large as a 

 man's hand. In the plot witUuut potash the leaves first 

 turn rod and then black, drying up and shrivelhug hke 

 those of the potatoes which have received the same treat- 

 ment." ViLLE. 



Special Manures and Jfecessiti/ for having a Well-Balancul 

 Mixture. 



*' On one plant in particular, viz., beetroot, I have varied 

 my experiments ad injinitum^ in the endeavour to increase 

 its saccharine richness, and have three times out of five, 

 obtained richer roots with potassic chloride associated with 

 ammonic sulphate than with potassic nitrate. These first 

 experiments justify my hope of one day seeing specific 

 functional manures practically apphed. We will now pass 

 from the general classification of manm-es and their reci- 

 procal relations to the study of the rules to be observed 

 in selecting the formuUo best suited to each kind of plant. 

 These rules ai-e necessiuily a repetition of those which I 

 have ah'eady laid before you, namely, to know the domin- 

 ant constituent of a plant, the proportion it is necessary 

 to employ, and the proper proportion of the subordinate 

 constituents." — ViLLE. 



Necessity for Careful I'^election and Change of Seed. 



" All the different species are susceptible of certain 

 changes which are capable of becoming hereditai'y. Kaces 

 and varieties have no other origin. Unimportant in a bot- 

 anical point of view, these deviations often become of great 

 importance in agriculture, because, under the same con- 

 ditions of soil and manm-e, one viu'iety often produces twice 

 as much as another. 



" For tlu'ee years I grew parallel patches of wheat, one 

 being English red wheat, the soil and the manure were 

 the same in both cases. The English wheat throve won- 

 derfully, whilst the other, notwithstanding the great caio 

 taken with it, tinned out badly. 



"During the autumn it always showed a marked advant- 

 age over the English soil, but in the spring, although some 

 late frosts occurred, it was attacked by rust, whilst the 

 English corn being less advanced took no harm whatever." 



— ViLLE. 



(SEED OOEN.) 

 {E.Ttractedfrom the "Field," loth October ISSS.) 



The selection of seed most suitable for cUmate and soil 

 is a subject of grave importance to the Engli.sh farmer, 

 inasmuch as the success or failure of our crops depends 

 in a large measure on our judgment in this matter. A\'c 

 are mostly aware of the influence of selection, and our 

 faith in the value of pedigree corn in transmitting its prii- 

 perties in some measure to its offspring influences our clioice 

 of seed; but it is not generally known that the climate 

 in which our seed corn is produced may have a material 

 influence on its value. A highly interesting report on this 

 subject is appended to the catalogue of Swedish seeds ex- 

 hibited at the Amsterdam Exhibition by L. J. Wahlstedt, 

 the Swedish Commissionei-, from which we shall briefly quote. 

 The essay, originally in Swedish, has been translated into 

 French by J. H. Kramer. After describing the topogi-aphy, 

 climate, and soils of his country, the commissioner goes 

 on to state that for a long time it has been known as a 

 tact, that various plants grew best when the seed came 

 from more northerly latitudes. This question has recently 

 received careful consideration by scientific men. During 

 more than thirty years Professor Schiibler, of Christiania, 

 has given us his researches, not only as regards cereals and 

 common vegetables, but also as to a number of plants 

 cultivated in many parts of Norway, up to the extreme 

 north of the country. The results of his researches may 

 be summed up as follows: — 



1. When a plant is gradually transported from south to 

 north, or grown at a. greater altitude above the sea, which 

 is the same thmg, it becomes after some years acchmatised, 



