Vol. X. No. 227 



THE AGRICULTURAL NEWS. 



13 



STUDENTS' CORNER. 



JANUARY. 



FiKsT Period. 

 Seasonal Notes. 



Useful work of observation may well be conducted, at 

 this time of the year, for the purpose of ascertaining the 

 extent to which various plants, both wild and cultivated, are 

 attacked by scale insects, and attempts should be made to 

 identify these, as far as possible. Descriptions of scale 

 insects are contained in Pamphlets Nos. 7 and 22, of the 

 Department Series, and students are advised to consult these, 

 with special reference to actual specimens that have been 

 collected by them for identification. What circumstances in 

 the life-history of scale insects tend to simplify the methods 

 to be used for their control and to prevent them from spreading 

 as quickly as they might, if such circumstances did not exist? 

 Where are the eggs of the scale insect to be found? What 

 insects often assist in the spread of scale insects, and what 

 purpose leads them to have this effect? 



Study the means by which the numbers of scale insects 

 are reduced, in nature. How would you ascertain if any 

 given collection of scale insects on a plant was being attacked 

 by insect parasites? I )iscu.ss the existence of such parasites in 

 relation to possible precautions to be taken in liurning old 

 cotton plants at the end of the crop season. Gain as much 

 knowledge as you can about the fungi that attack scale 

 insects; the chief of these that are known in the West Indies, 

 at present, are described in the Agricultural Nexvs, Vol. VIII, 

 pp. 299 and 411. It is not sufficient, however, merely to 

 gain acquaintance with these descriptions; specimens of the 

 fungi themselves should be collected and examined, as far as 

 is possible. The fungi are most easily seen when they are 

 producing spore-bearing liodies, and it is often noticed at this 

 time that the scales in connexion with which they are exist- 

 ing are dead, for the greater part. What reason may be 

 suggested for the purpose of explaining this? The student 

 .should satisfy himself as far as possible, that the mycelium of 

 such fungi actually penetrates beneath the scale insect that 

 has been attacked, For further information concerning 

 fungi parasitic on scale insects, see West Indian Jiulietin, 

 Vol. XI, p. 1. 



Make a careful study of a cane cutting, distinguishing 

 its different parts, and comparing its structure with that of 

 other stems, notably those of dicotyledons. To do this 

 properly, the pieces of stem should be cut downwards, both 

 through the centre and between this and the rind, as well as 

 across the diameter. What are the uses of the different 

 portions of the stem of the sugar-cane (1) to the plant, (2) 

 to the sugar maker* Observations of the kind described 

 may be extended usefully to include cuttings that have just 

 .sprouted. Examine several such cuttings, the .sprouts from 

 which are of difterent ages, and ascertain (1) what parts of 

 the cuttings give rise to the sprouts, (2) what becomes of the 

 material of which the original cutting was composed. Give 

 a list of the advantages and disadvantages that arise from the 

 circumstance that the sugar-cane is propagated vegetatively, 

 for commercial purposes. 



What are the chief signs of the presence of the following 



untoward circumstances, in regard to the sugar-cane: (1) 

 insufficient drainage, (2) root disease, (3) the moth borer? 

 State, in each instance, what you would do to put an end, 

 as far as possible, to the existence of such circumstances. 

 Describe exactly in what way the disease and the pest just 

 mentioned interfere with the nutrition of the sugar-cane, as 

 a plant. 



The subject of the diseases of cotton will have attract- 

 ed much attention on the part of those who are interested in 

 the growing of this plant. A general account of such 

 diseases is presented in the Agricultural Neivs, Vol. VIII, 

 p. 289, where several useful references in connexion with the 

 matter are given. Where a disease is present to any extent, 

 the amount of it in the difterent parts of the estate should be 

 indicated simply on some form of plan, and the distribution 

 of the disease in relation to the conditions that exist, particu- 

 larly in regard to soil, drainage and the kinds of crops grown 

 previously, should receive careful consideration. 



In a field of cotton, many of the bolls are, first of all, 

 seen to exhibit very small, reddish-brown spots, which become 

 larger, forming small, round areas, the middle of which 

 becomes dark in colour, while the edge remains reddish- 

 brown. Later, small pustul&s, or swellings, appear in th? 

 centre of the spot, which becomes dirty grey, or bright pink, 

 according to the numl>er of spores which develops. Some- 

 times, several spots are seen to run together, so that irregular 

 patches may be formed. What conclusions would you reach 

 in such a case, as to the disease which is attacking the cotton, 

 and what remedies against it would you propose to adopt? 



Questions for Candidates. 



PRELIMINARY QUESTIONS. 



(1) What practical advantage accrues from the possession 

 by certain plants of a cambium layer, and how does this 

 advantage arise? 



(2) Give an account of the composition of the air, with 

 especial reference to the needs of plants and animals. 



(.3) Describe an experiment by which the effect of lime 

 on heavy soils may be demonstrated. 



INTERMEDIATE QUESTIONS. 



(1) What kind of plant food is most likely to become 

 deficient, in ordinary soils? Give an account of the methods 

 that are employed to supply this deficiency. 



(2) Give a description of the ways in which .seeds are 

 dispersed in nature, and state in what ways such dispersal is 

 important to the agriculturist. 



(3) State broadly how decaying organic matter is 

 naturally employed in forming nitrates. 



FINAL QUESTIONS. 



(1) Give definitions of the .soil in relation to (a) the 

 plant, (b) the agriculturist. 



(2) Write an account of the general considerations and 

 practice with regard to weeds, on an estate. 



(3) State fully the uses that are made of the by-products 

 from an estate with which you are acquainted, and make any 

 suggestions as to their more economical employment. 



A review of a paper in the British Medical Journal, 

 Xo. 2.569, p. 771, gives the results of work undertaken 

 recently, by a French investigator, in order to gain informa- 

 tion as to the effect of baking bread on any disease 

 germs that it may contain. Several kinds of the latter 

 were added to dough, which was then baked. It was found 

 that the liaked bread contained none of the living germs, 

 so that it is considered that bread, on leaving the oven, may 

 be counted as a germ-free article of diet. 



