\/:/M/. CONSIDERATIONS 



In the third place. is tlir iitn*-ii!<i,- //-/<r, which may be divided into 

 >lri<i(i''l and /<i-/i->Y/-/<</<-</ i.ir xli-ij-il. and , / or tHUOth) J&Hre*. 



Lastly c >nies the in /v.-<.s //'//, which utl'cr> tu. a.-p'-et>: the white and 

 givy substance. The first is entirely formed l>y nerve lihre>. and the see did 

 by fibres and nerve cells. 



OM;\\S. The terra organ is given to un agglomeration of tissues 

 possessing a detennini'.te form, and having a function to fulfil. Organs ait 

 tlieivforo composed of tissues, as the tissues themselves are constituted by 

 anatomical elements. 



All animal organs are enclosed between two membrane-; named Umituri) 

 or teynweidurij Membra**, which are continuous with one another at the 

 margin of the natural opening*. These are the skin and the mucous 

 membranes, in whoso composition is included a layer of connective tissue 

 covered l>y an epithelium. 



Organs are distinguished into those which are solid, and those which arc 

 hollow. 



A "long the first, a certain number act as supports: such are the organs 

 formed by the connective tissue, and particularly the cartilages and bones. 



Others are destined to produce movements : these are the two kinds of 

 muscles. The action of the muscles is communicated directly to the 01 

 that are to ba moved, or it is transmitted through the medium of other 

 organs, such as the tendons and aponcnroses. 



The central nervous organs, nerves properly so called, and the vascular 

 glands, belong t'j this group of -solid organs. 



With regard to the hollow organs, they are everywhere covered by the 

 internal, tegumentary, or mucous membrane. Examples : the lungs and 

 stomach. There must also be included the vessels formed by elastic and 

 contractile membranes arranged as canals, in which the blood and lymph 

 circulate ; and, lastly, the serous membranes, which line the interior of the 

 splanchnic cavities, and cover the surface of the organs contained in them. 



APPARATUS. Organs are very numerous in the animal economy, and in 

 order to study them profitably it is necessary to classify them in a methodi- 

 cal manner, according to their physiological affinities. Consequently, there 

 have hci-n collect- d into a single category all those organ* which are destined 

 hieve the same physiological finality, and to such a group has been given 

 the name of ap^nratnx. 



An apparatus is, then, an assemblage of all those organs of an animal 

 which concur to the same end, and which serve for the accomplishment of 

 the same function. 



\\'e will successively describe, in the following order, the different appa- 

 ratus of which the organism is composed : 



1. Locomotorij 



3. Respiratory Apparattu : 



4. Urinary Di'j>iinit!ri- 



1 1 . Innervatory Ap}*iratu9 ; 

 7 . 



H. 



This description will l>u terminated by a brief exposition of tin- '<../<<// 

 /' Id,- j'.ilii* a ml it* 



