It is quite a mistake to suppose that, apart from the chlorophyll function, the physiology of the fungus-cell is fundamentally different from that of ordinary plant-cells.
In the herbals and older treatises on materia medica and therapeutics no explanation is usually offered of the action of medicines, and in such works as that of Cullen (1789) only a few of the more obvious actions are occasionally explained according to the current theories of physiology and pathology.
Dutrochet towards the middle of the century, and Liebig's application of chemistry to agriculture and physiology put beyond question the parts played by the atmosphere and the soil in the nutrition of plants.
Thus anatomy and physiology display the structure and functions of the human body, while psychology investigates the operations of the human mind.
He went first to University College, London; at Heidelberg he worked at German; at Berlin he studied psychology, metaphysics and also physiology under du Bois-Reymond, and heard lectures on Hegel, Kant and the history of philosophy, ancient and modern.
No such distinction of mental activities as that involved in the division of the study of animal life into morphology and physiology has ever really existed: the investigator of animal forms has never entirely ignored the functions of the forms studied by him, and the experimental inquirer into the functions and properties of animal tissues and organs has always taken very careful account of the forms of those tissues and organs.
In 1840 the appearance of Chemistry in its Application to Agriculture and Physiology by Justus von Liebig set on foot a movement in favour of scientific husbandry, the most notable outcome of which was the establishment by Sir John Bennet Lawes in 1843 of the experimental station of Rothamsted.
Besides those already mentioned, his works include An Outline of the First Principles of Horticulture (1832), An Outline of the Structure and Physiology of Plants (1832), A Natural System of Botany (1836), The Fossil Flora of Great Britain (with William Hutton, 1831-1837), Flora Medica (1838), Theory of Horticulture (1840), The Vegetable Kingdom (1846), Folia Orchidacea (1852), Descriptive Botany (1858).
For the physiology of fasting, see Dietetics; Nutrition; also Corpulence.
The year 1851, while he was lecturing on physiology at Konigsberg, saw the brilliant invention of the ophthalmoscope, an instrument which has been of inestimable value to medicine.