306 THE CAUSES OF THE XI 
words “organic nature.” In speaking of the 
causes which lead to our 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 “ Zquus 
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 eS mass of flesh. 
or what is technically called muscle, being the 
substance which by its power of contraction enable 
the animal to move. These muscles move the hare 
parts one upon the other, and so give that strength 
and power of motion which renders the horse se 
