closely associated with this? 12. Give a distinction between animals and plants as regards growth. The food of animals and plants. What is said in respect to size? 13. What important distinction in the effects of respiration of animals and plants? 14. What are the decisive distinctions between animals and plants?

15. Disease, which consists in an unnatural condition of the bodily organs, is in most cases under the control of fixed laws, which we are capable of understanding and obeying. Nor do diseases come by chance; they are penalties for violating physical laws. If we carelessly cut or bruise our flesh, pain and soreness follow, to induce us to be more careful in the future; or, if we take improper food into the stomach, we are warned, perhaps immediately by a friendly pain, that we have violated an organic law.

16. Sometimes, however, the penalty does not directly follow the sin, and it requires great physiological knowledge to be able to trace the effect to its true cause. If we possess good constitutions, we are responsible for most of our sickness; and bad constitutions, or hereditary diseases, are but the results of the same great law,—the iniquities of the parents being visited on the children. In this view of the subject, how important is the study of physiology and hygiene! For how can we expect to obey laws which we do not understand?

15. What is said of disease? 16. Why is the study of physiology and hygiene important?

17. In the structure of the human body, there is a union of fluids and solids. These are essentially the same, for the one is readily changed into the other. There is no fluid that does not contain solid matter in solution, and no solid matter that is destitute of fluid.

18. In different individuals, and at different periods of life the proportion of fluids and solids varies. In youth, the fluids are more abundant than in advanced life. For this reason, the limbs in childhood are soft and round, while in old age they assume a hard and wrinkled appearance.

19. The fluids not only contain the materials from which every part of the body is formed, but they are the medium for conveying the waste, decayed particles of matter from the system. They have various names, according to their nature and function; as, the blood, and the bile.

20. The solids are formed from the fluids, and consequently they are reduced, by chemical analysis, to the same ultimate elements. The particles of matter in solids are arranged variously; sometimes in fi´bres, (threads,) sometimes in lam´i-næ, (plates,) sometimes homogeneously, as in basement membranes. (Appendix A.)

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.

27. The term SYSTEM is applied to an assemblage of organs arranged according to some plan, or method; as the nervous system, the respiratory system.

22. Define a fibre. 23. Define a fasciculus. 24. Define a tissue. 25. Define an organ. What is the action of an organ called? Give examples. Mention other examples. 26. What is an apparatus? Give an example 27. How is the term system applied?