Most of our present knowledge of the embryological development of the salivary glands can be traced back to the detailed observations made by Chievitz, toward the end of the last century. His classic work “Beitrage zur Entwicklungsgeschichte der Speicheldrüsen", has been supplemented by the studies of Bujard (1911), Schulte (1913), Carmait (1913) and especially Thoma (1919). Relevant information may be found in articles by His (1885}, Hammar (1901), Paulet (1911), Florentin (1928), and more recently Thompson and Bryant (1950). All the above investigations were carried out in human embryos, but data is available as well for other species, such as the pig (Flint, 1901-02; Kallius, 1910; Moral, 1913), dog and cat (Falcone, 1898; Metzner, 1908, Aeberhardt, 1936), mouse and rat (Moral, 1915-16; Borghese, 1950a, 1950b).

The tracheo-bronchial system and lungs develop from the fore-gut. They commence as a ventral groove in the pharynx, which becomes roofed over to form the laryngeotracheal tube, lined by entoderm (49). The distal end of this tube grows downwards and forwards and divides into the two lung buds. These lung buds grow into dense mesenchymal tissue which forms the pleural coverings and part of the lung parenchyma. The tubular system develops by branching and re-branching to form a system of tubes in parallel, which averages about 23 generations in the human (131). The structure of the lungs is conventionally divided into the conducting and the respiratory parts. In many ways this is misleading, as there is an intimate anatomical connection which this physiological distinction tends to disguise.

In his review of 1946 Pitts (110) presented a concept of the central nervous control of breathing which accounted for many of the experimental observations made up to that time, and in particular for the phenomenon of maintained inspiration or apneusis seen in vagotomized animals sectioned at the midpontile level (69, 100, 112, 133, 137). According to the hypothesis propounded by Pitts there are anatomically separate inspiratory and expiratory centres in the medulla, located in close spatial relationship one to the other. These centres could be differentially activated by localized electrical stimulation of points in the medulla (112).

In man, maximum visual acuity is obtained when the image of the visual target falls on that part of the retina known as the fovea. This condition results when a subject "looks at" a stationary target with his eyes still, and the subject is then said to be fixating the target. The maintenance of visual fixation is relatively easy when both the target and the head are stationary in space. But with the introduction of target and head movement the problem of fixation becomes much more difficult and the requirement can only be met by close integration of several different physiological mechanisms. These are first the elaborate processes jointly referred to as body postural control, second the various patterns of neck reflexes controlling movement of the head on the shoulders, and thirdly vestibular and optokinetic reflexes controlling the angle of the eye in the head. [...]

Magnesium is a member of the alkaline earth metals (Group IIA of the Mendeléef Classification) but in many ways it has closer resemblance to zinc and cadmium (Group IIB). It is a light white metal of atomic number 12 and atomic weight 24.32. There are six known isotopes. Those with atomic weights 24, 25 and 26 are naturally occurring in the percentages of 79, 10 and 11. Those with atomic weights 23, 27 and 28 are radioactive. [...]

Although the first experimental demonstration of neuromuscular transmission was made in the second century A. D. by Galen (see Fulton 1926, chapter 1) the highly specialized nature of the neuromuscular junction remained unknown until the middle of the nineteenth century. Then in 1847 Wagner (see Couteaux 1960) discovered that motor nerve terminals, unlike their parent axons, are unmyelinated, and later work by Kuhne (1888) revealed that they lie in invaginations of the muscle fibre surface. The finding of Sokolow (1874) that chronic denervation causes motor nerve terminal degeneration and disappearance without affecting muscle fibre structure further illustrated structural specificity by suggesting a discontinuity between motor nerve terminal and muscle fibre. [...]

The established importance of cancer as a cause of human mortality has stimulated the development of a vast field of cancer research or oncology. The techniques and concepts which have been employed in attempts to gain a better understanding of malignant tumour transformation have come from almost every branch of the biological and biophysical sciences. In recent years the rapidly changing discipline of immunology has served as a ready source of new ideas for application to the problems of oncology. The present thesis represents a further attempt to utilize immunological techniques for the study of biological mechanisms underlying the development of cancer in the human host. [...]

This thesis represents an examination of indicator dilution curves in the liver, an organ with sinusoids completely permeable to virtually all molecular species. The three major parts of the thesis, examination of dilution curves for reference substances completely recovered in the outflow, and examination of dilution curves for sulfobromophthalein1 a substance not completely recovered in the outflow 1 and examination of the effect of catheter distortion upon dilution curves, are distincty separated in Chapters 2 to 4 to permit ease of publication of the material in 3 parts.

The material presented in this thesis has been the result of an original interest in abnormal alterations of the "tone" of skeletal musculature in human disease. Such alterations are generally observed as components of the symptom complexes of sorne of the common neurological diseases. Typical of such a disease entity, or syndrome, is that of Parkinson's disease. The latter is classically characterized by a generalized rigidity and involuntary tremor of part of the body musculature. [...]

This investigation was prompted by clinical reports of changes in hearing sensitivity in patients having recently undergone parathyroidectomy. It was thought that this might be associated with changes in the blood calcium concentration (Gannon, 1963). A search of the literature did not disclose any investigations into the role of calcium in cochlear function. [...]