Vol. X7I. No. 401. 



THE AGRICULTURAL NEWS. 



281 



•when an increased metabolization of iodine is 

 required, the thyroid may enlarge as a result of its 

 increased activity. This enlargement of the thyroid 

 appears most commonly at the period of adolescence. 

 The administration of iodine during that period, 

 however, may prevent thyroid enlargement, or if the 

 thvroid is already enlarged, it diminishes its size or 

 . may reduce it lo normal. In view of this fact and of 

 the fact that goitre is prevalent in some regions of the 

 United States, while in others it is rare, researches 

 have been made to know whether there is a difterence 

 between the iodine content of foods in areas where 

 goitre is prevalent as compared with areas where goitre 

 is ra'ely seen. The results of these investigations, 

 reported in Bulletin .'99 of the Ohio Agricultural 

 Expsriment Station, emphasize the variety and acci- 

 dental nature of iodine as a food constituent, and 

 indicate the necessity for a study of factors other than 

 the diet which affect the amount and ccJndition of the 

 iodine present in the thyroid, as promising results of 

 greater significance in relation to the cause of goitre. 



Annual Reports of the Society of Chemical 



Industry. 



The .Society of Chemical Industry has done wisely 

 in following the example of the Chemical Society in 

 initiating the compilation and issue of annual reports 

 on the progress of the various sections of applied 

 chemistry dealt with in its journal. It is a bold 

 venture to carry out such an undertaking in circum- 

 stances so unpropitious, and Nature of June 14, 1917, 

 welcomes with sincere pleasure the advent of an 

 enterprise which is bound to have a far-reaching 

 influence on the development of chemical industry in 

 all English-speaking countries. Its inception at the 

 present time is most opportune. Thanks to the energy, 

 skill, and perspicacity with which it is conducted, the 

 journal of the Society has become its most valuable 

 asset. It is certain that these annual reports are 

 destined to be a no less valuable feature of its work, 

 provided that those who control its affairs are deter- 

 mined to rise to the full e.xtent of their opportunity. 



Insecticidal Plants from the Tropics. 



In an article contributed by Professor Maxwell- 

 Lefroy to Tropical Life for June, it is remarked that 

 in most parts of the tropics one finds plants which are 

 known to the natives, and which they use for killing 

 fleas and vermin, or for keeping off flies and mos- 

 quitoes: rarely, as in India, one finds a plant reputed 

 to kill insects in water or to prevent white ants. 

 Such plants are worth investigation. Can they be 

 obtained in any quantity? Do they remain efficacious 

 if dried? What part of the plant is used.' Is it 

 available only at one season or alwajs? Such are the 

 questions to be asked, and it is necessary to know 

 exactly how the plants are used locally, and for what 

 purposes. All plants which have such properties, 

 which are available in a dry form in quantity at not 

 too excessive a price, are worth sending for trial 

 at the present time. 



Careers in Tropical Agriculture. 



The work of the British Empire Producers' Organi- 

 zation has, as is pointed out in a recent issue of 

 Empire Trade Notes, revealed the existence of a great; 

 • levelopment of technical application to tropical agri- 

 culture, and steps are being taken in association with 

 other institutions, to prepare a case for the establish- 

 ment of a chair in this subject at the University of 

 Glasgow and at one EnglisH'eentre, probably London or 

 Cambridge. Ours is the largest of tropical Empires, 

 and within its confines exist boundless resources in 

 such commodities as sugar, cotton, copra, rubber, etc., 

 which afford opportunities for immense industrial 

 developments. The study of scientific culture in regard 

 to such departments has been in the past carried on 

 much more thoroughly and systematically in foreign 

 countries, and it has been necessary to employ expert, 

 ability in highly paid positions. It is now felt that; 

 the careers that are open to specially trained young 

 men in these fields should be secured for the benefits 

 of our own people. The proper method of instruction 

 must necessarily include some knowledge of chemistrj' 

 and engineering, botany and entomology, in view of 

 the likelihood that more and more use will be made 

 of mechanical and biological methods in the future. 

 It is important that expert managers of tropical estates 

 should have full knowledge of any progress in the 

 design of suitable machinery for efficient production, 

 so that a course of study would include instruction in 

 that direction, and it would be necessary that a portion 

 of the time should be spent in the tropical regions 

 to attain proficiency. It is probable that such 

 a career will be peculiarly attractive to many of the 

 young men of the coming generation. 



^ 



Loss of Fertihzers by Leaching. 



Cultivated soils are subject to loss of fertility from 

 two main causes, the plant food contained in the crop 

 removed and that leached out of the soil by rain. 

 The amount of plant food removed by different crops 

 is well known; but the amount lost through leaching, 

 and also what elements of plant food are so lost are not; 

 so definitely known. Bulletin IS', for November 1916, 

 of the LTniversity of Florida Agricultural Experiment; 

 Station, contains a report of experiments undertaken 

 to obtain definite information on these points under 

 Florida conditions. As a result of five years' work the 

 following conclusions, amongst others, are stated: — 



Newly cleared land when exposed to heavy rain- 

 fall soon loses much of its fertility through leaching. 



The fertility of the soil may be maintained by 

 growing leguminous crops, and applying fertilizers. 



The greatest loss of fertility from unmanured 

 soils occurs with nitrogen, which leaches through in 

 considerable quantities. 



Lime is lost in considerable quantit3^ tending to 

 bring about an acid condition in the soil. 



Distribution of rainfall influences to a consider- 

 able extent, the amounts of the fertilizing constituents 

 which leach through. 



These conclusions, it must be remembered, apply 

 only to Florida conditions, and to soils similar in 

 character to that used in the experiments. 



