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.

It is recognised that oestrogen action plays a central role in the physiology and biochemistry of avian reproduction. Exogenous oestrogen has been shown to bring about striking changes in immature pullets, both in the morphology of the secondary sex organs, particularly the oviduct, and in the composition of blood and other tissues; the more obvious changes taking place in the latter include the involvement of the bony skeleton in the metabolism and transport of the materials of the egg yolk and egg shell and the production of yolk material by the liver. These matters have been the subject of reviews by Nalbandov (1953), Lorenz (1954), Sturkie (1958), Urist (1959) and van Tienhoven (1959). The similarity of these changes to those which occur at puberty in the normal pullet clearly indicates the presence of endogenous oestrogen in the domestic fowl.

In his studies on the isolated cell envelope or a marine pseudomonad, Brown (1960, 1961) observed decreases in the turbidity or suspensions or the cell envelopes when these were incubated at low buffer concentrations. Turbidity changes did not take place when the buffer concentration was increased. These decreases in turbidity or the cell envelope suspensions he interpreted to being due to degradation or the cell envelopes. A number or soluble products were released when the cell envelopes were incubated. The nature or these suggested to Brown that their release was due to the action or an enzyme. Since the release or these compounds was prevented by high buffer concentration, Brown suggested that lysis of the whole cells was due to the action of an enzyme residing in the cell envelope. Prevention of lysis of the whole cells by high salt concentration would then be due to the inhibition by salts of the action of a lytic enzyme.

Nitrogen tantalizes mankind with the paradox of poverty in the midst of plenty. All living things on this planet must have nitrogen in their food. The earth’s atmosphere contains far more than enough nitrogen to satisfy the requirement, yet relatively few of the species populating the earth are able to metabolize nitrogen from the atmosphere. This circumstance gives rise to important ecologic and economic consequences, and poses challenging questions for several branches of science. The first isolation of free living nitrogen fixing bacteria by Winogradsky and Beijernck stimulated attempts to assess the importance of non-symbiotic nitrogen fixation in the nitrogen economy of the soil. Though numerous papers have accumulated, they also provide opportunities for controversy ranging from polite disagreement to acrimonious debate, and most of them need careful reevaluation.

Coumarin (2-oxo-1,2-benzopynpl), a lactone of o-hydroxy-dis-cinnamic acid is a naturally occurring constituent of certain plants, especially sweet clover. Coumarin, present in "spoilt" clover, is sometimes ingested by livestock causing a haemorrhagic condition. Stahmann et al. (1941) identified dicoumarol as the active principle involved. Due to the strong structural relationship of dicoumarol with coumarin, Robert and Link (1937) believed that dicoumarol was formed from coumarin. Many of the coumarin derivatives are pharmacologically active and include anticoagulant drugs, rodenticides and insecticides. Due to its bitter taste and vanilla-like odour, coumarin itself has been employed for flavouring foods but its use has been discouraged owing to its damaging effect on the liver of animals.

By employing Koch's postulates, certain strains of Escherichia coli have been proven to cause enteritis of early weaned pigs. 1. Two strains of hemolytic E. coli were isolated consistently and in large numbers from the fecal samples of early weaned pigs that scoured shortly after weaning. 2. Symptoms of enteritis were reproduced artificially by contaminating the drinking water of the pigs with a live culture of one of the two strains of E. coli. The same strain of E. coli was isolated in very large numbers from the fecal samples of artificially infected animals. 4. The infection of this strain of E. coli was transmitted naturally by housing susceptible animals with the scouring animals. A hypothesis is put forward that certain strains of E. coli occur frequently as part of the normal intestinal microflora of swine and behave as typical infectious agents when suitable conditions for their growth are provided.

Water movement in clay soils is influenced by the volume changes associated with water content changes, and by the water retention characteristics of the soils. These properties are all dependent upon particle-size distribution. This thesis attempts to establish relations between texture and shrinkage, moisture retention, and permeability for a simplified soil system consisting of mixtures of clay and glass beads. Observations are explained in terms of the present theories for soil-water interactions. The thesis is subdivided into four chapters. The first chapter gives an account of present views on soilwater interactions, and is included to facilitate discussion in the later chapters.

The etiology of endemic pneumonia in rats has been investigated, and the specific cause of the condition was established. A viral agent was isolated in rat embryo skin primary tissue cultures, and postulates have been fulfilled for identifying this viral agent with endemic pneumonia in rats. Some characteristics of this virus were established. A method for demonstrating the cytopathogenic agent, involving two-step incubation of inoculated tissue cultures at two different temperatures has been described. This technique was successfully employed for the isolation of the virus responsible for endemic pneumonia in rats.