Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Working, as they do, harmoniously together, they form by far the most perfect mechanism known in nature. The actual physical machinery that does the work of the brain consists of cells, fibres, blood-vessels, drainage apparatus, and a connective substance which holds these —d Fig. i.—A Normal Brain Cell Of Large Size. a. Body of cell with innumerable minute fibres passing through it. 6. Its nucleus, c. Its nucleolus. d. The outgoing and incoming fibres through which it is related to other cells, to the spinal cord, and to the nerves of the body. all together in their proper places and prevents them being displaced or injured by such physical shocks as are implied in walking, jumping, or coming in contact with hard substances. The cells are the most important and the most wonderful of these. They have each an exquisite internal structure which it has taken fifty years ofhard and ingenious work by physiologists to discover, and we do not know it fully yet (see fig. i). The brain has to be first hardened by chemical agents and sliced into the thinnest shreds, stained with different coloured pigments Fig. 2.—A Large Brain Cell Prepared By A Different Process—The " Nissl Method "— From The One Shown In Flg. I. There are many methods of such preparation and staining, each bringing out the different parts and characteristics of the cell This one shows the cell full of material for potential work, "chromatic granules," such as a young man or woman in good health and after rest and sleep should have. a. Chromatic granules, b. Out- going and incoming fibres. and then examined by microscopes magnifying a thousand diameters to see the internal structure of the cell. Each cell has the power of taking up from the blood and storing within it the nerve substance for it...