Vol. IX. Xo. 207. 



THE AGRICULTURAL NEWS. 



109 



STUDENTS' CORNER. 



APRIL. 



First Peeiod. 



Seasonal Notes. 



Among the pests tliat attack the sugar-cane most com- 

 monly is the moth borer {Diatraea saccharalls). Opportun- 

 ties will probably be afforded at the present time for the 

 .study of this insect. Take note of the damaije that it does 

 to the sugar-cane and find out exactly in what way this 

 interferes with the life-processes of the plant. In what 

 stage of the insect's existence is it directly harmful/ Why 

 is it that this and similar pests are much more in evi- 

 dence during .some seasons than in others? In what ways 

 may this be helped to become a pest through the neglect to 

 remove the debris of plants other than sugar-cane! Informa- 

 tion concerning the tnoth borer of sugar-cane may be found 

 in the following places, among others: Ai/ricultwal News:, 

 Vols. I, pp. 3 and 50: II, p. 6.5: IV, p. 106,;"VI, p. 3, and VII, 

 p. 90: West Indian Jhillttin, Vol. I, p. 327 (where the insect 

 is well illustrated, in all its different stages): II, p. 41; VI, 

 p. 38; Lectures to Suyar Flmiters, No. VI; Pamphlet No. 1 

 of the Department Series. A useful experiment is afforded by 

 collecting some of the eggs (where are they usually laidi') and 

 putting them into a glass jar, which is closed afterwards by 

 tying a piece of muslin over the mouth. Note that some of 

 the eggs yield caterpillars of the moth, while from others 

 a small hymenopterous insect escapes. Account for the 

 latter fact. Introduce several of these insects into a similar 

 jar containing eggs of the moth borer that have been recently 

 laid, and make notes of what you observe during the next 

 few days. 



In the Students' Corner of the issue for December 11, 

 1909, reference was made to the selection of cotton plants in 

 the field for the purpose of obtaining good seed for the next 

 crop, and the method of effecting this .selection was outlined 

 broadly. In the case of a plant like Sea Island cotton, in 

 which self-fertilization takes place to a large extent, it is the 

 best plan, in any given locality, to obtain the seed for future 

 planting either from one plant or from plants that are as clo.se- 

 ly related as iio.ssible. Tliis method of selection gives plants 

 which show very little variation from one another. The 

 continuation of the method is likely to result in the acijuire- 

 ment of plants that are very constant in most of their 

 characters, at any rate, unless they are grown in a locality 

 other than that in which they originated. Even under these 

 conditions of rigid selection, it is found th.xt the plants will 

 vary among themselves in several respects, bat little attention 

 need be paid to this, if constant effort is given to the matter 

 of obtaining the best lint. 



Where opportunities are afforded, the student should make 

 himself familiar with the way in which sugar is manufac- 

 tured in his district; if possible, he should gain an insight into 

 other methods of manufacture, in order that he may be able 

 to institute comparisons between them. The chief object of 

 such comparisons will be to gain a knowledge of the advan- 

 tages and disadvantages of each system, and of the ways in 

 which the different methods of procedure affect the products 

 that are obtained. AVhieh of the processes is the best for the 

 production of marketable molasses? How does the manufac- 

 ture of sugar by steam boiling (the St. Croix method) reduce 

 the loss of sucrose as compared with that where the muscovado 

 method is employed! What is 'maceration', and how is the 

 extent to which this may be effected related to the expendi- 

 ture on fuel! 



Questions for Candidates. 



PKKLl.MIX.VRY IJUE.STION.S. 



(1) What uses for weeds are there in agriculture? 



(2) Describe any form of plough with which you are 

 familiar, mentioning the special uses of its different parts. 



(3) -What is meant by the physical properties of a soil! 

 Illustrftte your answer by reference to a clay soil and 

 a sandylsoil. 



IXTERMEDI.VTE (JUESTIONS. 



(1) Give the reasons for burying the cacao pods that 

 remain after picking. 



(2) Describe the different stages in the manufacture of 

 sugar by any method of which you know. 



(3) AVrite an account of the principal manures that are 

 used for providing phosi)horus, and say how each of them is 

 obtained 



PALO AMARILLO RUBBER. 



Notes on Palo Amirillo rubber (Euphorbia. ftUra, 

 Stapf) have appeareil in the Ai/ririUfurcd N'cii-n, Vol 

 VI, p. 313, and Vol. VII, p. 390. The additional 

 information which is given below is taken from the 

 Krw Bulletin, No. 9, 1909, p. 392:— 



Some particulars regarding this plant as a new source of 

 rubber appeared in the Ke/r llidhtin, No. 7, 1907, p. 294. 

 The following supiilenientary information upon the subject is 

 gathered from an illustrated article on ' The Rubber Plants 

 of Mexico,' by Dr. H. H. Rusby, in Ton-eya, Vol. IX, No. 9, 

 September 1909. 



From this paper it appears that the Palo Amarillo will 

 not grow upon the alluvial plains of Mexico, but only on tlie 

 rocky hillsides where the drainage is good. The bark is 

 described as being thick and succulent, at first smooth and 

 of a light yellowish-green colour. That of the trunk and 

 large branches soon excoriates in large, very thin, papery, 

 translucent sheets of an orange-yello.v, or orange red, colour, 

 which impart to the tree a shaggy appearance, and a colour 

 that has given the trunk its vernacular name ' palo amarillo', 

 or yellow trunk. 



The flowers appear in January or thereabout, before the 

 appearance of the new leaves, and the fruits mature in .lune 

 and July. 



As soon as the bark is wounded, a milky juice exudes, 

 which is very irritant, and capable of producing violent 

 inflammation of the eyes if it enters them, as it is quite liable 

 to do in spattering, when the tree is cut. 



The great value of this tree as a rubber producer lies in 

 its abundance over large area.s, and the proximity of the trees 

 to one another, facilitating collection of the milk, as well as 

 the ease with which it can be propagated, and the rapidity 

 of its growth. 



All that is necessary for propagation is to thrust the 

 newly cut branches into the soil, where they practically all 

 grow. From them the tree reaches its full size in from five to 

 .seven years. These considerations appear to incline Dr. Rusby 

 to the opinion that, if all other sources of rubber were to fail, 

 this one could probably supply the world's entire require- 

 ments. 



The properties of the ' palo amarillo" rubber are peculiar. 

 Taken by itself, it is of only medium quality, but mixed in 

 suitable proportion with other varieties, especially with Para 

 rubber, it markedly improves them. 



