21. The parts of the body are arranged into Fi´bres, Fas-cic´u-li, Tis´sues, Or´gans, Ap-pa-ra´tus-es, and Sys´tems.
17. What substances enter into the structure of the human body? Are they essentially the same? 18. What is said of these substances at different periods of life? 19. What offices do the fluids of the system perform? 20. What is said of the solids? How are the particles of matter arranged in solids? 21. Give an arrangement of the parts of the body.
22. A FIBRE is a thread of exceeding fineness. It is either cylindriform or flattened.
23. A FASCICULUS is the term applied to several fibres united. Its general characteristics are the same as fibres.
24. A TISSUE is a term applied to several different solids of the body.
25. An ORGAN is composed of tissues so arranged as to form an instrument designed for action. The action of an organ is called its function, or use.
Example. The liver is an organ, and the secretion of the bile from the blood is one of its functions.[1]
26. An APPARATUS is an assemblage of organs designed to produce certain results.
Example. The digestive apparatus consists of the teeth, stomach, liver, &c., all of which aid in the digestion of food.