commencing with the mouth, contains the gullet, the stomach, the long intestine, and all the rest of those internal apparatus which are essential for digestion ; and then in the same great cavity there are lodged the heart and all the great vessels going from it; and, besides that the organs of respiration the lungs. Let us now endeavor to reduce this notion of a horse that we now have, to some such kind of simple expressions as can be at once, and without difficulty, retained in the mind, apart from all minor details. If I make a transverse section, that is, if I were to saw a dead horse across, I should find that, if I left out the details, and supposing I took my section through the anterior region, and through the fore-limbs, I should have here this kind of

section of the body (Fig. 1). Here would be the upper part of the animal-that great mass of bones that we spoke of as the spine (a, Fig. 1). Here I should have the alimentary canal (b, Fig. 1). Here I should have the heart (c, Fig. 1); and then you see, there would be a kind of double tube, the whole being enclosed within the hide;

the spinal marrow would be placed in the upper tube (a, Fig. 1), and in the lower tube (d d, Fig. 1), there would be the alimentary canal (b), and the heart (c); and here I shall have the legs proceeding from each side. For simplicity's sake, I represent them

merely as stumps (e e, Fig. 1). Now that is a horseas mathematicians would say - reduced to its most simple 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, flesh 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 queerlooking 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 growing, decaying, and being replaced during the life of the animal. The tissue is constantly replaced by new material; and if you go back to the young state of the tissue in the case of muscle, or in the case of skin, or any of the organs I have mentioned, 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 modification of a tissue which can be readily divided into little particles of fleshy matter, of that substance which is composed of the chemical elements, carbou, hydrogen, oxygen, and nitrogen, having

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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 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).1

Fig.2.

In this exposition of what Huxley called the architecture of the horse, it is to be seen that the scale of treatment should depend upon the actual importance of the subject for the writer's purpose; not upon its physical size, and not upon its importance or unimportance for another purpose. This seems simple enough, but the temptation to violate the principle assails everyone. We like to write at length on some part of our subject, not because that part is important, but because we want to display our knowledge; or we shirk 1 Darwiniana (Appleton).

another part because, though it is important, we do not happen to have at hand material with which to develop it adequately.

Before leaving this exposition of Huxley's, we should note how once he reduces the scale of a part in order to give the reader a bird's-eye view of its topic, and so impress it on the reader's mind. He describes the general structure of the horse twice in succession. The first time he gives a comparatively full treatment. The second time he throws out every particular that can be spared, and reduces this notion of a horse to a cross-section, so simple that it cannot be misunderstood or forgotten.

EXERCISE 23. (Oral.) After reading the following passage, decide as to how far the principle it affirms applies to the life of Abraham Lincoln.

I have been led to dwell at some considerable length on the events and circumstances of these earlier yearstrivial though some of them may seem to be- for more than one reason. In the first place, it always appears to me that the experimental period of boyhood and youththe period when so much is attempted in a more or less serious way, and so little actually done - forms by far the most fascinating portion of the biography of any man who has left his mark upon the world. The early struggles, the repeated failures, the uncertainties, disap

pointments, doubts, the ofttimes long and wearisome searching for the life-work which is dimly felt to lie somewhere in readiness for the ready but as yet unguided hand-these things are full of the picturesqueness of romance, and, while they arouse the interest of all, possess for the young, the ardent, and the ambitious, a world of inspiration also. And, in the second place, just as this period is the most attractive for all readers, so, too, it is beyond question the most important for those who desire to study a great mind in the process of its development, to surprise something of the secret of its power, and to realize and measure the subtle forces and influences which played their part in its education and consolidation. Beyond this, also, we have to remember that, in order to do justice to the record of any life, we must beware of being misled by the desire to secure an artificial balance among the different divisions of our sketch. It is often well worth while to linger over the earlier years, even at the expense of thrusting into a few paragraphs the actual accomplishments of after-life. For the period of achievement, no matter how brilliant that achievement may be, is after all only the period of translation into present fact of the impulses and powers which, even from the cradle, have been gathering in silence against the time when the moment for manifestation should arrive. Hence, for this period a brief outline is often enough; while the long years of preparation, during which the nature is plastic and every detail tells, require and should properly receive a fuller treatment at the biographer's hands.-W. H. HUDSON: The Philosophy of Herbert Spencer.

EXERCISE 24. (Oral.) Let the following outline be considered that of a theme 3000