student is referred to the larger text-books, as Quain's Anatomy and Carpenter's Physiology, to which works, among many others, I have to acknowledge my indebtedness. With the exception of the diagrammatic representation of nerve-endings in Plate VI., and one or two others, the source of which has been acknowledged, all the illustrations are taken from specimens in my possession. LONDON, April 22nd, 1882. CONTENTS. Classification of Cartilage-Temporary Hyaline Carti- lage-Articular, Costal, White and Yellow Fibrous Cartilages - Physical and Chemical Composition PAGE Microscopical Appearances and Minute Structure of Bone-Physical Properties and Chemical Compo- Structural Elements of Nerve Tissue-Varieties of Nerve Fibres, their Microscopical Appearances and Minute Structure-Nerve Cells-Structure of Ganglia Central and Peripheral Terminations of Nerves-Tactile Corpuscles, Pacinian Bodies, End Classification of Muscle-Parts of a Muscle- Micro- scopical Appearances and Structure of Muscle, Fibres, and Fibrillæ - Connexion of Fibres with their Tendons-Vascular Supply - Nerves and Lymphatics of Muscles-Structure of Unstriated Muscle and of the Muscular Fibre of the Heart- THE TISSUES AND THEIR STRUCTURE. CHAPTER I. Origin of the Tissues-Animal and Vegetable CellsProduction of Cells-Protoplasm - Classification of Tissues. IN beginning a description of the structure of the tissues of organized bodies, we may, without entering into any unnecessary discussion, state, that the result of research in the past has been to show that the various tissues and structures met with in plants and animals, however complex and differentiated they may ultimately become, originate, one and all, by means of elementary corpuscles, which have been named cells. These cells are capable of undergoing certain transformations, according to the conditions under which they are placed, and the functions they have B to perform. They remain separate in the fluids, but are usually grouped together in the solids. In some cases they undergo but little change, while in others, becoming differentiated to a greater or less degree, they produce the various modifications of form and structure met with in the animal and vegetable textures. The cells of the early embryo of plants consist of, 1. An external investing envelope or membrane-the cell-wall. 2. Within this a semi-fluid granular material -the protoplasm or cell contents. 3. Imbedded in this a more sharply defined body- the nucleus, which differs from the surrounding protoplasm in not being contractile. 4. Occupying the interior of the nucleus may be observed one, or sometimes more, distinct refracting particles-the nucleoli. The cells of the animal embryo consist of a granular, protoplasmic substance inclosing a nucleus, which, in turn, contains one or more nucleoli. From this description it will be seen that there is a distinct difference |