GENERAL STRUCTURE OF THE ANIMAL BODY. / 



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 apparatus 

 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 apparatus, 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 spermatic 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 

 spermatic 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. 

 But as all vertebrate animals have the same general plan of organiza- 

 tion, there is a marked similarity both in form and structure among 

 corresponding parts of different animals. Hence it is that in the 

 study of human anatomy a knowledge of the form, construction, and 

 arrangement of the organs in different types of animal life is essential 

 to its correct interpretation ; also it is that in the investigation and 

 comprehension of the complex problems of human physiology a 

 knowledge of the functions of the organs as they manifest them- 

 selves in the different types of animal life is indispensable. As many 

 of the functions of the human body are not only complex, but the 

 organs exhibiting them are practically inaccessible to investigation, 

 we must supplement our knowledge and judge of their functions by 

 analogy, by attributing to them, within certain limits, the functions 

 revealed by experimentation upon the corresponding but simpler 



