OF ORGANIC NATURE. 11 



which is composed of the chemical elements, carbon;^ 

 hydrogen, oxygen, and nitrogen, having such a shape 

 as this (Fig. 2). These particles, into which all 

 primitive tissues break up, are called 

 cells. If I were to make a section of 

 a piece of the skin of my hand, I should 

 find that it was made up of these cells. 

 If I examine the fibres which form the iig. 2. 



various organs of all living animals, I should find that 

 all of them, at one time or other, had been formed out 

 of a substance consisting of similar elements ; so that 

 you see, just as we reduced the whole body in the gross 

 to that sort of simple expression given in Fig. 1, so we 

 may reduce the whole of the microscopic structural 

 elements to a form of even greater simplicity ; just as 

 the plan of the whole body may be so represented in a 

 sense (Fig. 1), so the primary structure of every tissue 

 may be represented by a mass of cells (Fig. 2) . 



Having thus, in this sort of general way, sketched 

 to you what I may call, perhaps, the architecture of 

 the body of the Horse (what we term technically its 

 Morphology), I must now turn to another aspect. A 

 horse is not a mere dead structure : it is an active, 

 living, working machine. Hitherto we have, as it were, 

 been looking at a steam-engine with the fires out, and 

 nothing in the boiler ; but the body of the living 

 animal is a beautifully-formed active machine, and 

 every part has its different work to do in the working 

 of that machine, which is what we call its life. The 

 Horse, if you see him after his day's work is done, is 

 cropping the grass in the fields, as it may be, or munch- 

 ing the oats in his stable. What is he doing? His 



