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Show ~ 0 'l'HE :PRESENT CONDITION ple expression. Carry that in your minds, if you please, as a simplified idea of the structure of the Horse. The considerations which I have now put before you belong to what we technically call the' Anatomy' of the Horse. Now, suppose we go to work upon these several parts,fiesh and hair, and skin and bone, and lay open these various organs with our scalpels, and examine them by means of our magnifying-glasses, and see what we can make of them. We shall find that the flesh is made up of bundles of strong fibres. The brain and nerves, too, we shall find, are made up of fibres, and these queer-looking things that are called ganglionic corpuscles. If we take a slice of the bone and examine it, we shall find that it is very like this diagram of a section of the bone of an ostrich, though differing, of course, in some details; and if we take any part whatsoever of the tissue, and examine it, we shall find it . all has a minute structure, visible only under the microscope. All these parts constitute microscopic anatomy or 'Histology.' These parts are constantly being ·changed; every part is constantly O'rowino- decayino· ~ b b' bJ and being replaced during the life of the animal. The t issue is constantly replaced by new material; and if .YOU go back to the young state of the tissue in the ease of muscle, or in the case of skin, or any of the organs I have 1nentioned, you will find that they all come under the same condition. Every one of these microscopic filaments and fibres (I now speak merely of the general character of the whole process)-every one of these parts-could be traced down to some ~odi~cation of a tissue which can be readily divided Into httle particles of fleshy matter, of that substance •• OF ORGA~IC 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 J!'I G. 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 w0 n1ay 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 (Pjg. 1), so the primary structure of every tissue may be Tepresented by a n1ass 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 tenn 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 wero...,', 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 . . ' ~rapping the grass In the fields, as it may be, or munch- Ing the oats in his stable. vVhat is he dojng? His |