H.—29.

Meanwhile commercial supplies of limonite intended for stock consumption are being analysed periodically for cobalt to ensure that they are satisfactory in this respect. Surveys of the deposits at Okaihau and Ruat.angata have shown that the different seams or irregular masses vary greatly in cobalt content, but that by selection of the ore the resultant, ground product may be maintained at a level of at least 100 parts per million of cobalt. Material of this standard has proved efficaceous throughout the " bush sick " area. Combined with equal parts of salt it makes a lick of good consistency and attractive to stock. The colouring - power of the limonite helps the farmer to detect which animals are taking the lick by the staining of the hair of their faces. A number of trace elements are present in these limonites and may reinforce the action of the cobalt. There is little or no danger resulting from the animals consuming quantities in excess of their requirements. It appears, therefore, that the use of limonite possesses advantages over the use of a pure cobalt salt combined only with common salt. To some extent its use may be displaced by top-dressing with fertilizers containing cobalt, but salt-licks are beneficial to stock on most classes of country, and the addition of limonite to the salt even in districts not considered "bush sick" may be advantageous and entails very little extra labour or expense. Samples of the deposit of soft limonite at Maketu, Bay of Plenty, have been analysed and found to contain only 1-3 and 3-6 parts per million of cobalt. This figure was considered too low to warrant the expense of feeding trials. Border-line Bush-sick Areas. —At the request of the Arohena Branch of the Farmers' Union a visit was paid to that district. Soil and pasture conditions were found to be very similar to those in the neighbouring Ngaroma district, the soils being silts and sandy silts. Evidence is accumulating that much of the area of pumice-covered hills to the north of Hawke's Bay and east of the Huiarau Range is slightly affected with, bush sickness. Only sheep develop marked symptoms, and where tried, limonite lick has proved very beneficial. It is anticipated that farmers throughout this area wolild derive much profit, from the liberal use of limonite and salt as a stock lick and that the sheep and cattle carrying capacity of the district as a whole could be greatly increased thereby. Cobalt in Foodstuffs. —The demonstration that bush sickness is connected with a deficiency of cobalt has raised the question whether it is possible to prove by experiments on small animals that this element is essential in animal nutrition. In conjunction with the Research Officer in Animal Nutrition at Wallaceville, an endeavour is being made to select a diet of purified foodstuffs extremely low in cobalt. If this endeavour be successful feeding experiments on rats will be carried out at the Veterinary Laboratory. A number of samples of foodstuffs, both in their original condition and after special, purification, have been analysed for cobalt content. Although very low figures for cobalt have been found on a number of these foodstuffs there are still some difficulties to be surmounted before the experiments can be commenced with reasonable prospect of success. Some of the figures found which may be of interest are as follows (average cobalt parts per million dry weight) : Butter, 0-013 ; lard, 0-007 ; castor sugar, 0-010 ; cod-liver oil, 0-004 ; wheat-germ oil, 0-007 ; corn starch, 0-003 ; casein, 0-011 ; dried yeast, 0-038. lodine Survey of New Zealand Live-stock. —The third of the series of papers under this title, dealing with the Canterbury Province, by Mason and Waters, has been published in the Transactions of the Royal Society of New Zealand. The analyses of all the glands collected has now been practically completed, and the results for the remaining districts are in course of preparation for publication. Glands are still being received in connection with lick experiments in Southland and occasional outbreaks of goitre in farm stock. One such, occurrence recently reported was among sheep on a farm on peaty country near Orini in the Waikato. The only general tendency towards low iodine in glands from the Auckland Province previously noted was also on farms in the same locality. General. —A paper was read to the Sheep Breeders' Conference at Massey College and subsequently published in the report of the proceedings entitled Deficiency Diseases and Composition and Uses of Stock Licks." Bureau of Animal Nutrition. —Replies were secured from the various research organizations in New Zealand dealing with animal nutrition to a questionnaire sent out by the Bureau of Animal Nutrition asking for a summary of such work in progress in New Zealand, and were compiled and transmitted for publication by the Bureau. The Auckland meeting of the Australian and New Zealand Association for the Advancement of Science provided an opportunity for meeting many overseas delegates, especially from Australia, who are working on problems of animal nutrition akin to those found in New Zealand. Many useful discussions were held, and a paper was read entitled " Notes on the Toxicology, Methods of Estimation, and Biochemistry of Zinc," which has been the means of stimulating interest in this subject. Suspected Mineral Deficiencies connected with Plant Diseases. Zinc-deficiency (Chlorosis of Citrus and other Trees). —It has recently been found by a number of investigators in the United States, Australia, and elsewhere that certain types of chlorosis, or mottling in citrus and other fruit-trees, are connected with zinc deficiency in the soils on which the trees are growing and are curable by applications of zinc salts either in a spray or to the soil. In view of the occurrence of chlorosis in certain citrus orchards in New Zealand an investigation is being made jointly by the Department of Scientific and Industrial Research and the Horticulture Division of the Department of Agriculture into the possibility of this chlorosis being connected with zinc deficiency. A large number of samples of chlorotic "and

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