Before the advent of isotopes in biological research, the elements making up the bodies of adult animals were presumed to be more or less static, being replaced only slowly. Food substances, on the other hand, were thought to be rapidly used up and their residues excreted. The use of isotopes soon indicated that the elements comprising all parts or the body had a rate of turnover which varied somewhat, but was often much higher than expected. Radioactive calcium has become available in recent years and has helped to elucidate further the behaviour of calcium in metabolism.

In 1947 an investigation on soil genesis was initiated at Macdonald Collage with the objective of obtaining information regarding the mechanism of the formation of podzolic soils under forested conditions. A starting point in this investigation was the hypothesis that substances leaching from the litter of the forest floor would be of especial importance in this process by, (a) contributing to the organic matter content of these soils, especially in the B horizon, and (b) being involved in the translocation of iron and aluminum within the profile.

The production of good quality milk powders is a relatively recent enterprise. Although reference to edible milk powder dates back to the thirteenth century, it was not until the early twentieth century that milk powders were produced in any appreciable quantities. This comparatively slow development of the dried milk industry can be attributed to the inherent difficulties involved in the manufacture of whole milk powder of a satisfactory keeping quality.

The use of organic pesticides* on fruit and vegetable crops is widespread. Residues of the pesticides are frequently present when the fruits and vegetables are marketed as foods. Since many pesticides are toxic to humans, it is necessary to have methods for the detection and measurement of pesticide residues on foods. Analytical procedures for the determination of pesticide residues ordinarily involve the following steps: (a) extraction of the pesticide with a suitable solvent; (b) purification of the extract; and (c) the performance of qualitative and quantitative analyses for the pesticides.

The serum hexosamine and protein contents of avian, bovine, porcine, rodent (rat) and human subjects were estimated. Significant species and sex differences were detected. Maturation brought a large increase of serum hexosamine in female fowls and pigs, a small increase in cows, and no increase in humans. The effects of pregnancy in cows and exercise and diet in rats were also studied. In another study the effects of gonadal hormones, administered to immature fowl, on the levels of serum hexosamine, protein, glucuronic acid, sugar and calcium were investigated. Hydrolysis of serum with a polystyrene resin gave higher estimates of hexosamine content than hydrolysis or serum with 4 N hydrochloric acid and subsequent chromatography. A reliable estimate of the glucuronic acid content ofserum could not be obtained by a direct determination, but a relatively reliable estimate may be obtained after resin hydrolysis of serum and purification of hydrolyzate by passing it through cationic and anionic exchange resin columns.

It has been realized for many years that egg yolk is remarkable for its high content of phosphoprotein. However, considerable uncertainty has existed as to the number and nature of the proteins present in egg yolk. Most of the more recent studies have distinguished two lipoprotein fractions, which have been designated as 'lipovitellin' and 'lipovitellenin'; at one time lipovitellin was regarded as a phospholipophosphoprotein, but more recently it has been realized that the older lipovitellin preparations included a phosphoprotein of relatively very high (about 10%) phosphorus content.

The fact that sulphur is an essential element for the growth of all plants points out the importance of sulphur studies in soils. It has been shown that sulphur is needed in amounts of the same order as phosphorus, even greater sometimes, by most crops. An investigation of the sulphur status of Quebec soils was initiated at Macdonald College in 1957. Particular attention was paid to the methods of total sulphur and sulphate determination. It was concluded (58) that no signs of deficiency seemed to occur in these soils. The distribution of sulphur in soil profiles has been studied by various workers (30, 70, 74). Relatively high sulphate contents in subsoils have been found (30) and the availability of this sulphur to plants was demonstrated.

Interest in the sulphur status of soils stems from the fact that sulphur is an element essential for the growth of all plants. Although sulphur deficiencies have not so far been reported in the Province of Quebec, they are of considerable importance in some areas of North America, and the prevailing trend towards use of more concentrated fertilizers containing little or no sulphur in incidental impurities, has caused some workers to wonder whether such deficiencies should in the future be expected to occur in the province.

The proteins of the hen's egg are classical objects of chemical and biochemical research, partly because of the ready availability and practical importance of the egg, but also because of its great scientific interest. As a consequence, the state of knowledge regarding the proteins and lipoproteins of the egg tends to be an expression of the prevailing state of knowledge of proteins in general. A special feature of the yolk proteins that has attracted attention from the outset of serious chemical study of the yolk is the presence of an unusually high proportion of protein containing relatively high amounts of protein-bound phosphorus. Material obtained by dilution precipitation of yolk and subsequent removal of lipid by extraction procedures was round to contain around 1% phosphorus.

Commercial drying of milk dates back to the midnineteenth century, and since then, much research has aimed at the improvement of the quality of milk powder. This has been especially true since the Second World War, when there was a great demand for dry milk products of high stability and good dispersibility. The process of "instantization" has made possible the production of spray dried skim milk powders which are readily dispersible in cold water. However, little progress has been made towards the production of a readily dispersible whole milk powder. Previous investigations have shown that the wettability of a milk powder decreases as the particle size of the powder decreases.