



A 



SYSTEM OF HUMAN ANATOMY. 



CHAPTER I. 

 INTRODUCTORY. 



BY THE EDITOR. 



ANATOMY (derived from avarsjjt-vsiv, to dissect) is the science which 

 Beaches the structure and relation of the different parts of an organized 

 body. Organized bodies are divided into animal and vegetable ; hence 

 we have animal and vegetable anatomy, the latter being closely allied to 

 botany. 



An organized body consists of an assemblage of parts called organs, 

 which have a mutual relation to, and dependence upon each other ; each 

 doing its part to sustain the organism which they compose. The descrip- 

 tion of the form, colour and position of these organs is the province of 

 special anatomy; whilst their relations to each other, and the knowledge 

 of the number and arrangement of organs in particular parts, constitutes 

 regional or topographical anatomy, which, when taught with reference to 

 surgical operations, is usually designated by the title of surgical anatomy. 

 When these organs are carefully examined, they are found to consist of a 

 number of different structures which serve to build up and constitute 

 them. These are called tissues, and are either general, existing in all the 

 organs, or special and peculiar, and found only in certain of them, giving 

 them their appropriate characters. The knowledge of tissues, their form, 

 colours, constituents, origin and uses, constitutes histology ; which, com- 

 mencing with Bichat in 1790, has now attained such an extent and im- 

 portance as to constitute almost a new science, and to correct and bring 

 nearer to perfection the hypotheses of its sister science, physiology. 



An animal body or organism consists of solids, which differ in density 

 and hardness, in consequence of being more or less mingled with and di- 

 luted by the fluids which permeate them. 



By the agency of chemistry we may separate both solids ond fluids into 

 proximate and ultimate elements, and hope by this means to obtain a 

 more intimate acquaintance with their structure and use ; but if this is 

 done with the masses as is usual in chemical analyses, and not upon the 

 tissues separated from each other by the aid of the microscope, it will 

 confer upon us about as much real and useful information, as the analysis 

 which a scientific but witty English chemist once made of a whole mouse. 



The principal ultimate elements of an animal body obtained by the pro- 

 cesses of chemical analysis are 



Oxygen, hydrogen, carbon, and nitrogen, which form almost the whole 

 oulk of the fluids and soft solids ; but to these must be added a number 



