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.

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.

Hormones are classified according to their physiological actions rather than by their chemical structures. It is now more than 30 years since estrone was isolated from human pregnancy urine. This was the first isolation of a hormonally active steroid front natural sources. Shortly thereafter, two other estrogenic steroids, estradiol and estriol, were isolated from human nregnancy urine, and related estrogenic steroids were isolated from horse urine. Since all these estrogens were steroids, it became customary to speak of the "naturally occurring estrogens" with the implication that such substances were steroids. [...]

The presence in a plant of factors which are capable of inducing estrus in animals was first reported by Loewe et al. (1927) in 1926. This fact, however, did not attract much attention until during World War II, when sheep in Australia, grazing on pastures of subterranean clover (Trifolium subterraneum), showed severe breeding disorders (Bennetts et al., 1946). [...]

Proteins containing carbohydrates are widely distributed in animal tissues. Such diverse compounds as serum proteins, mucins, blood group substances, pituitary hormones and connective-tissue elements are protein-carbohydrate complexes. The carbohydrate part of these complexes are aminopolysaccharides, that is polysaccharides containing hexosamine.

Proteins are essential in human nutrition. Many circumstances arise, however, where the needs of the body are not satisfied by the normal dietary intake. Hypoproteinemia may occur where there is impairment of the function of some body organ, such as the liver, kidneys or alimentary tract. [...]

The process of soil podsolization has been studied for over one hundred years but much of the chemistry involved still remains obscure. Two questions which remain unanswered concern the manner of mobilization of iron and aluminum of the A horizon and of their precipitation in the B layer. [...]

Clay materials have been used by man for many centuries, especially in the fields of ceramics and agricultural industry. In ceramics, clays provided a source of raw material for pottery and brick making. [...]

Podsol soils have been intensively studied ever since the middle of the last century, yet the mechanism of their development is still obscure. In view of this lack of knowledge regarding podsolization and because these soils are the dominant agricultural soils of Eastern Canada, an investigation of the fundamental processes responsible for their development was started at Macdonald Collage in 1947. [...]

The effect of hydrogen ion concentration in the hydrolysate on the products of extraction in the Dakin butanol fractionation has been studied, using acid hydrolysed casein. Maximum extraction occurred at pH 5. Tyrosine, phenylalanine, valine, methionine, and leucine were most easily extracted over the range pH 2-10. [...]