Vol. IX. No. 219. 



THE AGRICULTURAL NEWS. 



301 



STUDENTS' CORNER. 



SEPTEMBER. 



Secoxd Period. 

 Seasonal Notes. 



Leguminous and other plants are being grown, during 

 the jiresent time, on the land which will be used subsequently 

 for the cultivation of main crops. Reference has been made 

 several times to the particular usefulness of leguminous plants, 

 in this connexion, on account of the property which they 

 possess of harbouring nodule-forniing bacteria that take 

 nitrogen from the air and hand it on to them in such a form 

 that they can make use of it. An important fact 

 necessary to understand, in relation to the.se minute organ- 

 isms, is that they usually exist in most soils, but that there 

 are several varieties of them, each of which acts in conjunction 

 with a definite plant. This e.xplains why the first few crops 

 of a leguminous plant that has been introduced newly into 

 a country are often small, even though the conditions of 

 climate are suited to it. Fortunately, the bacteria, as they 

 complete several generations in a short time, quickly show 

 changes in their characteristics when the conditions under 

 which they are living are altered. In other words, the number 

 of generations that are necessary for any definite results of 

 evolution to show themselves are speedily completed, so that 

 different varieties are soon obtained. This is fortunate, because 

 it gives a means of providing a suit:ible variety of nodule- 

 forming bacteria where new leguminous plants are introduced 

 ■where this does not occur already. This means is simply to 

 grow several crops of the new plant in the .same soil, one after 

 the other, when, if this soil contains any nodule forming 

 bacteria at all, there is a likelihood that these will change 

 their characteristics in such a way as to become useful to the 

 new jtlant. The process can be e.xtended eventuall}', by 

 scattering some of this soil over other areas where the 

 plant is to be raised, thus sowing it with the right kind of 

 bacteria. Attempts have been made, as is well known, to 

 form cultures of the nodule-forming bacteria, so that they 

 may be sent where they are required on account of the absence 

 ■of the organisms from the soil. By making cultures is meant 

 getting the bacteria from the nodules on the roots of the 

 leguminous plants, separating them from other living organ- 

 isms that may be present, and giving them the best chance 

 of increasing their numbers by supplying them with suitable 

 food. This is a comparatively simple matter ; the great dirti- 

 culty arises when it is attem[)ted to prepare these cultures in 

 such a way as to enable the bacteria to be sent long distances, 

 and to arrive still living; no particular success has been 

 obtained, so far, with such artificial methods of preparation. 



.Make observations, as far as you can, on the effect on 

 the succeeding crop of the employment of green dressings. 

 Give a list of all the ways in which such dressings may be 

 beneficial to the soil. Discuss the advisability of employing 

 these where the rainfall is small. 



Consider, as far as you can, the direct effect of too great 

 and too little rainfall on the parts of plants above the ground. 

 How is the amount of rainfall, during the chief period of 

 flowering of cacao directly related, for instance, to the number 

 of pods that will be borne? liemember that rainfall has to be 

 considered not only in reference to the condition of the soil, 

 but to effects of the kind just mentioned, and to the influeuee 

 that it ha.s on insect life. The last consideration is especially 



important in relation to cotton. What connexion exists be- 

 tween the precipitation and the amount of shade to be pro- 

 vided, where this is necessary? Give an account of the life- 

 processes of the plant that are bound up intimately with the 

 matters brought forward by this cjuestion. 



In going through a cacao plantation, it is noticed that 

 some of the pods on a few of the trees in a small area show 

 round, brown patches; in other cases, the biown colouration 

 has spread all over the surface of the pod; while in the worst 

 instances, the rind, beans and pulp have been destroyed. What 

 reason would you give for these appearances of the pods, and 

 what suggestions would you make, in orderto lessen the chances 

 that other healthy parts of the plantation shall suffer loss in 

 a similar way? 



Give an account of the life-history of the honey bee, 

 comparing it in a broad, general way with that of the ant. 

 What are the chief circumstances to be taken into considera- 

 tion when the advisability of keeping bees is under notice? 



Provide a description of the arrangement of an apiary 

 to suit the conditions surrounding the place where you live. 

 Mention any ways in which bees are useful to agriculturists. 



Questions for Candidates. 



PRELIMINARY QUESTIONS. 



(1) Slate whether it best to obtain cuttings for planting 

 sweet potatos from those grown from cuttings or from roots. 



(2) Explain why good drainage of the soil is necessary 

 to the successful growth of crops. 



(.3) Give as many reasons as you can for propagating 

 plants by grafting. 



INTERMEDIATE QUESTIONS. 



(1) Discuss the advantages and disadvantages of the 

 presence, to any extent, of stones in a soil. 



(2) Mention how the cells of the vegetativelj' growing 

 parts of plants are increased in number. 



(3) State how observations on a germinating cotton .seed 

 may give indications as to the best conditions for its sowing 

 on a large scale. 



FINAL QUESTIONS. 



(1) Give an account of the chief points that merit 

 consideration when the suitability of a given piece of land for 

 cacao cultivation is being decided. 



(2) In relation to the employment of artificial manures 

 for maintaining soil fertility, what possible alternatives exist, 

 and why are they limited in their application ? 



(3) Give your idea as to the most advantageous arrange- 

 ment of the various buildings on a lime plantation producing 

 concentrated juice in fire-heated pans. 



The Journal of the Board of Agriculture for August 

 1910, p. 412, gives an account of a new type of milk- 

 preserving machine that was exhibited at the Bordeaux Agri- 

 cultural Show in May 1910. The principle employed in the 

 machine is the exposure of the milk to a very high pressure, 

 with subsecjent pasteurization, so that the fat globules are 

 crushed and mixed so completely with the water in the milk 

 that they cannot be separated, and it is consequently impossi- 

 ble to obtain cream from such milk. Its great advantage, 

 however, is that it will keep in boitles for an indefinite 

 length of time. 



