Page:Popular Science Monthly Volume 71.djvu/116

110 end." Still more clearly does the variety of cells which actually exists in a hair show in the following picture, which represents a cross-section of a hair, and its follicle, but more highly magnified than were the hairs in the previous figure. The adult body consists of numerous organs. These are joined together and kept in place by intervening

substance. The organs themselves consist of many separate parts which are also joined by a substance which keeps them in place. This substance has received the appropriate name of connective tissue. We find in the adult that it consists of a considerable number of structures. There are cells and fibers of more than one kind, which have been produced by the cells themselves. There is more or less substance secreted by the cell which helps to give consistency to the tissue. In some cases this substance which is secreted by the cells becomes tougher and acquires a new chemical character. Such is the case, for instance, with cartilage. Or, again, you may see a still greater chemical metamorphosis going on in the material secreted by the cells in the case of bone, where the substance is made tougher and stronger by the deposit