306 THE CAUSES OF THE 



XI 



words " organic nature." In speaking of the 

 causes which lead to oar present knowledge of 

 organic nature, I have used it almost as an 

 equivalent of the word " living," and for this 

 reason, that in almost all living beings you can 

 distinguish several distinct portions set apart to 

 do particular things and work in a particular way. 

 These are termed " organs/' and the whole 

 together is called " organic." And as it is 

 universally characteristic of them, the term 

 " organic " has been very conveniently employed 

 to denote the whole of living nature, the whole 

 of the plant world, and the whole of the animal 

 world. 



Few animals can be more familiar to you than 

 that whose skeleton is shown on our diagram. 

 You need not bother yourselves with this " Equus 

 caballus " written under it ; that is only the Latin 

 name of it, and does not make it any better. It 

 simply means the common horse. Suppose we 

 wish to understand all about the horse. Our 

 first object must be to study the structure of the 

 animal. The whole of his body is inclosed within 

 a hide, a skin covered with hair ; and if that hide 

 or skin be taken off, we find a great mass of flesh, 

 or what is technically called muscle, being the 

 substance which by its power of contraction enables 

 the animal to move. These muscles move the hard 

 parts one upon the other, and so give that strength 

 and power of motion which renders the horse so 



