22 TEXT-BOOK OF PHYSIOLOGY. 



together with the diaphragm and the walls of the chest, constitute 

 the respiratory apparatus, the function of which is the introduction 

 of oxygen into the blood and the elimination from it of carbon dioxid 

 and other injurious products. The kidneys, the ureters, and the 

 bladder constitute the urinary apparatus. The skin, with its sweat- 

 glands, constitutes the perspiratory apparatus, the functions of both 

 being the excretion of waste products from the body. The liver, 

 the pancreas, the mammary glands, as well as other glands, each 

 form a secretory apparatus which elaborates some specific material 

 necessary to the nutrition of the individual. The functions of these 

 different physiologic apparatus e. g., digestion, absorption of food, 

 elaboration of blood, circulation of blood, respiration, production 

 of heat, secretion, and excretion are classified as nutritive junctions, 

 and have for their final object the preservation of the individual. 



The nerves and muscles constitute the nervo-muscular apparatus, 

 the function of which is the production of motion. The eye, the 

 ear, the nose, the tongue, and the skin, with their related structures, 

 constitute, respectively, the visual, auditory, olfactory, gustatory, and 

 tactile apparatus, the function of which, as a whole, is the reception 

 of impressions and the transmission of nerve impulses to the brain, 

 where they give rise to visual, auditory, olfactory, gustatory, and 

 tactile sensations. 



The brain, in association with the sense organs, forms an appa- 

 ratus related to mental processes. The larynx and its accessory 

 organs the lungs, trachea, respiratory muscles, the mouth and 

 resonant cavities of the face form the vocal and articulating appa- 

 ratus, by means of which voice and articulate speech are produced. 

 The functions exhibited by the apparatus just mentioned viz., 

 motion, sensation, language, mental and moral manifestations are 

 classified as functions of relation, as they serve to bring the individual 

 into conscious relationship with the external world. 



The ovaries and the testes are the essential reproductive organs, 

 the former producing the germ-cell, the latter the sperm element. 

 Together with their related structures, the fallopian tubes, uterus, 

 and vagina in the female, and the urogenital canal in the male, 

 they constitute the reproductive apparatus characteristic of the two 

 sexes. Their cooperation results in the union of the germ-cell and 

 sperm element and the consequent development of a new being. 

 The function of reproduction serves to perpetuate the species to 

 which the individual belongs. 



The animal body is therefore not a homogeneous organism, but 

 one composed of a large number of widely dissimilar but related 

 organs. As all vertebrate animals have the same general plan of 

 organization, there is a marked similarity both in form and struc- 

 ture among corresponding parts of different animals. Hence it is 



