Vol. X. No. 245. 



THE AGKICULTDRAL NEWS. 



301 



. STUDENTS' CORNER. 



SEPTEMBER. 



Second Pepjod. 

 Seasonal Notes. 



The gathering of the lime crop ati'ords un opportunity 

 for making observations on the relation between the yields 

 that have been obtained and the manures u.sed. For 

 purposes of comparison, the conducting of these should only 

 be done in relation to plants which arc similarly situated and 

 in a state of good healtii. It is probable that, while such 

 work is being carried out, indications will be obtained as to 

 the eliects of ditierent kinds of manure in relation to insect 

 attacks, particularly invasions of scale insects. The results 

 of all such observations should be employed for the purpose 

 of outlining a scheme for manurial experimentation for the 

 coming sea.son. 



Those who work on lime estates should ascertain the 

 acidity of the raw lime juice, in grains per ounce, and in 

 ounces per gallon; the way in which this is to be done may 

 be explained by the Agricultural Officers. Note that the 

 acidity of concentrated lime juice is ahva}'^ expressed in 

 ounces per gallon. The best concentration is considered to 

 correspond with 95 to 105 ounces per gallon.. Why is the 

 concentration not carried much further? Iii'preparing the 

 best qualities of such juice, it is filtered after concentration, 

 and this is done most successfully and quickly while it is 

 still warm. 



In connexion with the attacks of scale in.sects on limes, 

 careful observations .should be made for the purpose of dis- 

 covering, and gaining a knowledge of, the fungus parasites 

 which assist in keeping these in check. Where the attacks 

 of the insect are serious, branches containing parasitized scales 

 are often placed in the affected tree, and the process has been 

 been unfortunately referred to as ' inoculation '. Discuss the 

 advisability of the employment or otherwi.se of this word in 

 the special connexion. 



In cotton fields, a careful lookout should be kept for 

 pests, particularly for the leaf-blister mite, whose initial 

 attacks may be easily overlooked, so that time is given for 

 a serious spread before its discovery. What treatment should 

 be adopted when the presence of leaf-blister mite is ascer- 

 tained in the fields? In what way does this pest interfere 

 with the life-activities of the plant, and how is it spread? 



Where onions are grown, careful observation should be 

 made on the way in which the seed is planted and the young 

 plants are transplanted into the field. A useful investiga- 

 tion is to make an experiment to find if there is any 

 advantage in transplanting instead of sowing directly in the 

 fields. What precautions may be taken in order to prevent 

 the seed from being carried away by ants, and why should 

 the soil in the seed boxes or nursery beds be as free as 

 possible from the .seeds of weeds? Give an account of the 

 procedure in connexion with the growing of a crop of onions 

 and the preparation and packing of the produce for export.. 



Discuss the respective merits of such plants as you have 

 seen grown for the provision of green dressings, including in 

 the discussion the time taken by the plants to reach 

 maturity, the insect pests by which each kind is attacked, 

 ^nd the best means for controlling these pests. It is 

 a useful matter to con.sult the reports of trials with green 

 dressing plants in other islands, with a view to the introduc- 

 tion of such among them as may appear to be best suited to 

 Ijhe conditions under which they are required to grow. Upjer 

 what circumstances is the application of green dressings to 



soil likely to be most successful, and in what cases may 

 actual damage result from such application? 



Questions for Candidates. 



PRELIMINARY QUESTIONS. 



( 1 ) Give a brief account of the life-hist^y of three plants 

 that are raised from cuttings. ■ " ' ' ■ 



(2) In what ways does the provision of good drainage 

 benefit the .soil? ■ ... 



(3) Why are plants propagated by grafting ? ' 



INTERMEDIATE QUESTIONS. 



(1) What is the nature of the losses sustained by soil 

 through the removal of water by drainage ? 



(2) Describe, with the aid of drawings, the development 

 of any plant that you have raised from a cutting. 



(3) What special care would you give to a newly grafted 

 plant i' 



FINAL QUESTIONS. 



(1) Describe those parts of a stem of a plant that are of 

 the greatest importance in enabling it to be raised by vege- 

 tative means. 



(2) Of what advantage is uniformity in estate produce, 

 and in what ways may such uniformity be obtained, under 

 conditions with which you are familiar ? 



(3) Describe a system of draining the land, for any cropi 

 with which you have had experience. 



EXPERIMENTS IN THE EXTRACTION OF 

 MANIHOT GLAZIOVII LATEX. 



Two experiments of this kind have been made recently 

 at Kalamu, near Boma, in the Lower Congo, with trees, in 

 the first case, growing in a sandy hollow. The results, which 

 are given in the Bulletin Agricole du Congo Bvlge, for June 

 1911, p. 359, show that in the first experiment made in the 

 dry season, employing 129 trees, the yield of latex was 

 12'9 gallons, equivalent to 327 Bb. of dry rubber; the 

 renewals of the tapping were made during twenty-nine days. 

 It was noticed that, during this trial, the latex was much 

 thicker and richer in rubber than in the one to be described. 

 A circumstance rarely observed in regard to Manihot was 

 noticed, namely a decided increase in the yield of latex 

 after the first four renewals of the tapping; toward the end 

 of the trial a gradilal diminution occurred in the quantity 

 collected daily. A former experiment, made on the same 

 trees during the rainy season, gave a yield of 14"6 gallons 

 of latex, or 28'3 R. of dry rubber. 



The second trial was made in the dry season, employing 

 242 trees, situated on a plateau possessing a clay soil with 

 pebbles. The tapping, repeated for ten days, gave 276 lb. 

 of dry rubber. 



In the two experiments, the latex was coagulated to 

 form sheet rubber by the employment of-3 per cent, of its 

 volume of 'formol'. The rubber was kept for a quarter of 

 an hour in water at 80° C, then passed through the press 

 and well washed with water. The report of the experts to 

 which the samples were submitted showed that the rubber 

 had exactly the same appearance as that shown by Hevea 

 rubber from the Far East. It was valued at 2s. 5c?. per lb., 

 with Para at 5s. 10c?. 



The wounds from tapping healed normally in the case 

 of most of the trees. With some, however, the bark dried 

 up, and cracks were produced in it, the wounds thus formed 

 being attacked by insects. 



