3S8 



THE TROPICAL AGRICULTURIST. [Dec. i, 1886. 



the water passes up the alburnum, or j'ouug outer 

 layers of woolly tissue, moreover, a diruiuution of 

 supplies from the leaves meaus less substance and 

 poiver for replacing the root-hairs, ami so on. In this 

 way it may require some time to kill the tree, and 

 all kiads of complications may arise meanwhile. This 

 case is probably by no means uncommon. A more 

 extreme case is where the soil becomes damp and 

 cloj^ged with excessive moisture ; not only does no 

 oxygen reach the roots, but noxious gases accumulate 

 in solution in the soil, and will hurrj' matters by 

 poisoning cells which might otherwise live a longer 

 life of usefulness. It is extremely probable that such 

 gases find their way into higher parts of the plant 

 in the air-bubbios known to exist and to undergo 

 alterations of pressure in the vessels of the wood: 

 this being so, they would .slowly retard the action 

 of other living cells, and so affect the upper parts 

 of the plant even more rapidly than would otherwise 

 be the case. Damp soil may thus do injury according 

 to its depth and nature; but it need not necessarily 

 be deep to be injurious if much oxygen-consuming 

 substance is present. I have seen excellent soil con- 

 verted into damp, stinking, deadly stuff, from the 

 action and accumulitiou of the larvio of cockchafers : 

 thef e " grubs " may, it is true, accelerate the devastation 

 cauhsi by the consumption of oxygen and the accu- 

 muliit on of poisonous waste matters in the soil by 

 directly cutting off portions of the roots themselves, 

 but the accumulation of oxygen-consuming substance, 

 and the cutting off of supplies to the root-hairs 

 evidently plays a chief part in the destruction. 



There is another matter with regard to damp soils 

 thai, cannot be left out of account. I have already 

 told you that roots which are developed in water, or 

 in very damp sandy soil — and which are perfectly 

 healthy— have few or no root-hairs formed on their 

 surfaces; whereas it may be readily shown that the 

 roots of the same plant growing in a well ai-rated 

 open soil, which is scarcely moist to all appearance, 

 will be densely covered with a close set pile of hairs, 

 iudeed it is by meaus of the mdlions of root-hairs 

 on its n otiets that a Sunflower or a Bean, for ins- 

 tance, obtains the enornnus quantities of water 

 nece.s.sary for its needs from soil, which to our rough 

 perception, seems to be dry. I cannjt here go into 

 all the proofs that such a sail is by no means sj 

 dry as it looks; but will simply remind you of what 

 was said above as to the enormous force with which 

 the minute particles of rocU, &;., which form " soil " 

 retain their hold on the thin films of water which 

 constitute what have been termed their water-blankets. 

 This is certain, that a healthy, well-rooted plan can 

 take up water from a soil which is to ail appearance 

 air-dry; whereas a plant which has not yet had time 

 ti) (ievelope its root-hairs in sufficient numbers to 

 take these firmly adherent water-films from numerous 

 pirticles of soil would, droop and wither. Of course 

 it must be borne in mind that we are speaking of 

 land-plauf-s such as we commonly meet with on 

 or.linary dry land ; in the case of plants which flourish 

 in bogs or in water there are corrtspondii'g differences 

 in the structures of their roots agreeing with the 

 ilitfeiences of environment. Even such plants need 

 air at their roots, and an excellent illustration of 

 this is afforded by sonifj Willows. O.ir common Osier 

 and Willows grow, as you are aAiiro, in low-lying, 

 dam)i, and even boggy places, often flooded ; now it 

 has been found that, if young Willows are planted 

 too (Uep in the soil, they very soon send out new 

 roots — adventitious roots they are often called— close 

 to the surface of the soil, and these roots soon do 

 all the work. There is no doubt that this power 

 enables these "W'illows to live in places that would 

 be fatal to them otherwise ; and the same is true of 

 home other plants. 



El ough has now been said to show you how necessary 

 it is that seme care should be exercised in watering 

 plants, or in exposing them to conditions different 

 Irom those to which they are accustomed ; and, it 

 r.icd scarcely be ad led, apparen'ly mysterious diseases 

 ni:iy son:ptimes be explained when it is shown that 

 fciich precautions haye been peglectecj. Any one cm 



quote instances of plants which will grow in sonje 

 soils and not in others, but no very satisfactory reason 

 is afforded by simply saying that the one soil is suitable 

 and the other not : however, all I have attempted to 

 show you is that some soils are not suitable for some 

 plants because the plants in question need mofe air 

 at the roots than these particular soils can affoid 

 them under the circumstances. — H. Makshai.l WaUD , 

 M.A., F.J..S. — Uardciuirs Chronicle. 



{To he continued.) 



QUINOLOGICAL WOEK IN THE MADEAS CIN- 

 CHONA PLANTATIONS. 



JIV DAVID HOOPER, F.C.S., 



(jovi rtunent QuinoIo(/ist. 



Last year I communicated to the Oonfereuec at Aber- 

 deen the results of some experimeiits made in the 

 cultivation of cinchona. A number of analyses were 

 given of the different varieties of bark grown on the 

 (.lovernment and other estates. It was shown how 

 the alkaloids were distributed in old succirubra trees ; 

 and it was noticed how natural shade and the pro- 

 cess of mossing promoted the increase of alkaloids in 

 the bark. Some of these conclusions were perhaps 

 not altogether unknown before, but I thought it 

 desirable to confirm results which are liable to vary 

 under different conditions of age. Another year's 

 work sliows some more extended investigations into 

 the effect prdouced on alkaloids by the renewal of 

 bark and by the manuring of trees, and tables are 

 compiled from numerous analyses showing the rise of 

 alkaloids in growth and their deterioration by age 

 and other causes. I have again been permitted to 

 quote extracts from my annual report, which has lately 

 been forwarded to Government through Jlr- Lawson, 

 Director of the Cinchona Plantations. 



Renciral ly <S/tarui(/.— Shaving cinchona trees has been 

 for some years a method of harvesting bark which 

 in some districts works better than that of stripping 

 and mossing. The cellular and richer portion of the 

 bark is removed in this way, and the librous portion 

 is left. The bark thus treated thickens again, and 

 the shavings, taken from it are fouu 1 to bo richer 

 still in alkaloids. The analyses of some succirubra 

 shavings taken from trees grown in the Ouchterlony 

 Valley will show to what an extent trees may be 

 improved by this method. The renewals were taken 



afier intervals of twelve months 

 fore lasted over three years. 



Quinine. 



1-35 

 2-4t) 

 3-GO 

 3-87 



the experiment there- 



Original bark 

 Once renewed 

 Twice renewed 

 Thrice renewed 



The increase of 

 year by renewing 

 not so prominent in 

 good, and indicates 



Other 

 Alkaloids. 

 5-87 

 4-22 

 3-99 

 3-71 



Total. 



G-68 



7-59 



7-58 



quinine during the first and secDnd 



is most satisfactory; the increase is 



the third year, but the bark is 



that shaving for at least four 



years might be permitted. The trees upon which these 

 experiments were made were six years old when the 

 original bark was taken. If at this comparatively early 

 age they are not injured by shaving, and renew their 

 bark so well, it is not desirable to wait for the trees to 

 become more matured. 



When trees are allowed to grow until they are over 

 twelve years of age, and then shaved, the renewal set in 

 more slowly, and the resulting bark does not compare 

 more favourably with the original bark than if the tree 

 operated upon had been half the age. This may be 

 instanced by quoting some more analyses. Last Decem- 

 ber some interesting samples were sent by the manager 

 of the Glenrock Company, 8. E. Wynaad, consisting of 

 some natural and renewed shavings of succirubra taken 

 from trees of six and twelve years of age. The follow- 

 ing is the analysis of four of the samples : — 



Sulph. T, . . 



