968 



THE TROPICAL AGRICULTURIST. 



[June i, 1883. 



The Swedish Goverument has granted a sum of £60 for 

 this year, t-o an entomologist, whose duty it will be to 

 advise farmers as to the beat means of destroying in- 

 jurious insects. — Nature. 



The Taeo Plant, which constitutes the principal 

 article of diet amongst the natives of many of the South 

 Sea islands, has been cultivated for years on many of the 

 sugar plniitntinns of this colony for the use of kanakas. 

 It has not come into general consumption amongst the 

 white poijidation, although it is said to be a very healthy 

 vegetable, equal, if not superior, to the sweet potato. 

 It has recently been introduced into some of the Southern 

 States of America, where it is not only relished as a 

 vegetable, but has been found a most excellent food for 

 horses and cattle. The taro grows to greater jjerfection 

 in the islaml of Tanna thau in any of the other islands, ou 

 account of the great depth and freeness of soil in tliat 

 island. The natives cvdtivate it, Uke the yams, on the 

 tops of mounds of fuiely pulverised earth. "When gro\™ 

 on laud cultivated by the plough, it is usual to plant it 

 on the tops of large drills prepared by hilUng up together 

 three or four furrows. A very good starch and a very 

 fair arrowToot are made from the bulb. It can only be 

 cultivated with success, however, on fine alluvial soil such 

 as are to be found along the banks of rivers in this colony. — 

 Qtteendander. 



Coco-nut Fibke for potting Oattleyas and other Orchids 

 has Ijcen tried at Broomfield, Chelmsford, with the most 

 lamentable results. When, with Mr. Warner, over twenty 

 years ago we made a series of very careful exjieriraents 

 with the whole husk, the roughly broken husk and the fibre, 

 and the result in each case proved that the end thereof 

 was death to all the Orchids experimented ou if they were 

 not shaken out and repotted in the usual way. Notwith- 

 standing the.se experiments, Mr. Warner has recently used 

 it largely, and it has proved an exj^ensive experiment to him, 

 as it will to all who are beguiled into trjing it. It is strange 

 that these pranks should be played always by old and clever 

 growers; one seldom sees the beginner depart from the 

 tried and proved methods. A few years ago I saw a very 

 large collection reduced to misery by the use of coco-nut 

 fibre mLxed with sphagnum, and since that I saw that the 

 grower who hail produced some of the iinest specimens in 

 the North when he used peat and sphagnum, had potted 

 a great number of his plants in sphaguiun mixed with 

 what seemed to be road scrapmgs. My experiments show 

 that, when kept ch-y, cocoa-fibre gets covered with a white 

 inould, and when wet with a gelatinous fungus, either of 

 is poison to the roots. When dry it is next to impossible 

 to thoroughly wet it, and the har.sh fibres cripple the roots 

 wherever they touch them. If any one wants to earn a 

 testimonial from the Orchid growers let him tell them 

 where they can get the good old Orchid peat they used to 

 get: there must be plenty of it in the British Isles. I 

 have seen fine samples from Sweden and Norway : if it 

 cannot be got here, I think it would pay some one to get 

 some over.— -J ABIES O'Beien. — Ganhiwrs' Chronicle. 



Pineapple Culture in Queensland. — Very tew people 

 have any idea of the possible yield with pineapples where 

 the climate and soil favom- their production. It has been 

 recently stated by a Mr. Rodda, after an m.spectiou of a 

 pineapple patch, that an acre of soil would yield over 

 10,000 fruit in the season, and, where a plantation is 

 well e.stablished, and the plants in their prime, this is 

 not an over estimate. On an average of 5ft. from plant 

 plant an acre would carry 1,750 plants per acre. The 

 fii'St year two to each plant would be a good yield, the 

 second year tour or six, and after that strong plauts will 

 often give from eight to twelve pineapples in the year, 

 if not all at one time at intervals during the season. So 

 then the first year's yield would be 3,500, the second year 

 from 7,000 to 10,000, and the third year, if eight or twelve 

 fruit were produced on each stool, the yield would be 

 14,000 or 21,000. Startling though these figures may ap- 

 pear, they are nuite within reach with good cultivation ; 

 with the neglect so frequently attendant upon pineapple 

 and banana cultm-e, however, the half of this is a high 

 average. But taking 10,000 as an average crop, and the 

 low rate of Is. per dozen as the market value, one acre 

 of pineapples would realise over £40, which is a good 

 letulu for the laboiu; and outlaj ueccssary to produce 



them. It has always been a matter of surprise to us that 

 the cultivation of this dehcious fruit has been so much 

 neglected, especially wheu the fact, so frequently brought 

 to hght, that Queensland-grown pineapples are equal, if 

 not superior, to those grown in Florida or elsewhere is 

 taken into consideration. The cidtivation necessary for 

 a five-acre plantation, and everything to be done ettiei- 

 ently, could be easily compassed by one man, breaking 

 the laud up deeply in the fii-st instance with the plough 

 followed by the subsoiler. Coast lands in Southern Queens- 

 land are very well adapted for this fmit if the soil is 

 deep, rich, and drained thorouglily. — Queensla aJer. 



What leaves are to trees, is shown, and the disastrous 

 influence of leaf disease, on tree life can be inferred, 

 from the following introductory paragraph to au article 

 in Xature: — "The leaf is the essential and really active 

 part of the ordinary vegetal organism: it is at once the 

 mouth, the stomach, the heart, the lungs, and the whole 

 vital mechanism of the euthe plant. Indeed, from the 

 strictest biological point of riew every leaf must be re- 

 garded as to some extent au individual organism by itself 

 and the tree or the herb must be looked upoii as an 

 aggregate or colony of such separate units bound together 

 much in the same way as a group of coral polypes or 

 the separate parts of a sponge in the animal world. '' 

 The writer, Mr. Grant Allen, goes on to describe the 

 functions aud food of leaves after a fasliion calculated to 

 impress us deeply mth the importance to a tree of a^ 

 plentiful supply of healthy foUage. We confess that we 

 never, previously realized so vividly the value of carbon 

 as plant food. " The gieat function of a leaf is the 

 absorption of carbonic acid from the ah, and its de- 

 oxidation under the influence of sunlight. From the free 

 carbon thus obtained, together with the hydrogen liber- 

 ated from the water in the sap, mauufactm-es the hydro- 

 carbons which form the mass of its various tissues. 

 Vegetal life in the true or green plant con.sists merely 

 in such deoxidation of carbonic acid and water, and 

 rearrangement of their atoms in new forms, impljiing 

 the reception of external energy ; and this external energy 

 is supplied by sunlight. AVe have thus two main couditions 

 affecting the shape and size of leaves: first, the nature and 

 amoimt of the supply of carbonic acid; and second, the 

 nature aud amount of the supply of sunshine. But as 

 leaves also aid and supplement the roots as absorbers of 

 water, or even under certain circum.stances perforin that 

 function almost entu-ely alone, a third and subordinate 

 element also comes mto play in many cases, namely, 

 the natm-e and amount of the supply of watery vapour 

 in the an-. This last element, however, we may leave out 

 of consideration for the present, confining our atentii n 

 at the outset to the first two. t!arbonic acid is the 

 true food of plants: water, one may say, is only their drink. 

 The roots can almost always obtain a suff cient amount of 

 moistm-e; aud though no doubt there is sometimes a fierce 

 struggle for this material between young plants, yet its effects 

 are not usually so obvious or so lasting on the shape of the 

 parts concerned. But for the carbon of which their tissues 

 must be built up, there exists a competition between plants 

 as great aud as evident as the competition between carnivores 

 for the prey tliey per.sue, or between herbivores for the 

 gi-asses and fruits on wliich they subsist. The plaint en- 

 deavom-s to get for itself as much as it can of this fund- 

 amental food stuff ; and all its neighbours enrteavoiu- to 

 frustrate and to forestall it in the struggle for aerial 

 nutriment. Again, the earbou is of no use without a 

 supply of sunlight in the right place to deoxidise it and 

 render it available for the use of the jjlant. Hence these 

 two points between them mainly govern the shapes of 

 leaves. Natm-al selection insures in the long run the 

 survival of those types of fohage which are best fitted 

 for the jierf ormance of their fimctious - as mouths and 

 stomachs in the particular environments that each species 

 affects. Accordingly, in the final result each plant tends 

 to have its chlorophyll disposed in the most economical 

 position for catching such sunlight as it can secure; and 

 it tends to have its whole absorbent surface ilisposed in 

 the most advantages position for drinking in such par- 

 ticles of carbonic acid as may pass its way. The import- 

 ance of the fijst element has always been fully recog- 

 nised by botaui.sts ; but the imoprtance of the second 

 appeals liitlierto to have been too fiequcutly overlooked. " 



