Axum

“ But men, at last, were so much used to the alteration, as to know it better than under its primitive form, and the engraving became what we may call the first elements, or root, in preference to the original.
The reader will see, that, in my history of the civil wars in Abyssinia, the king, forced by rebellion to retire to the province of Tigré, and being at Axum, found a stone covered with hieroglyphics, which, by the many inquiries I made 418 after inscriptions, and some conversations I had had with him, he guessed was of the kind which I wanted. ”

“ The lower ramus is really more horizontal than the upper (which used to be called the horizontal ramus) , and runs backward and outward from the body to meet the ramus of the ischium and so form the subpubic arch.
The ischium (fig. 16) , like the ilium and pubis, has the fundamental form of a three-sided prismatic ischium. rod. One extremity (the upper) completes the acetabulum, whilst the lower forms the large V. prominence, or tuber ischii. The surfaces of the bone are internal or pelvic, antero-external, and postero- external. The pelvic and postero
the innominate bone. ”

“ I suspect that the ilium is broken in the middle, and, as a consequence, that the distance from the posterior to the anterior ends of the visible parts of the bone (6⋅6 inch) is somewhat greater than it should be. Hence the acetabulum probably appears to be longer than it naturally is. The postacetabular process (c) , which should articulate with the ischium, is swollen and thick, but thins off, above and behind, into a thin vertical plate, the posterior curved margin of which is broad and turned in, like a narrow shelf. ”

“ Birds have a very large pelvis and its characters are constant throughout almost the whole group. The ilium is very large, and is united along its whole length with the sacral and pseudosacral vertebrae. The ischium is broad and extends back parallel to the ilium with which in most [340] birds it fuses posteriorly, further forward the ilio-sciatic foramen separates the two bones. In Tinamus, Hesperornis, Apteryx (fig. 65, B, 2) , and Struthio, the ischia are separate from the ilia along their whole length except at the acetabulum ”

“ The ischiadic portion consists generally of five or six nerves, which leave the pelvis as one thick system through the ilio-ischiadic foramen. The last nerve which contributes to the ischiadic plexus leaves the spinal column in most birds either between the two primary sacral vertebrae, or just below the hindmost of them, and sends a branch to the pubic portion which is composed of post-ischiadic nerves, partly imbedded in the kidneys, and innervates the ventral muscles between the tail and pubis, together with those of the cloaca and copulatory organs. ”

“ The three bones which form each side of the pelvis are known as the ilium, or hip bone, sometimes termed the aitch bone; secondly, the ischium, or sitz bone, being the bone by which the body is supported in a sitting position; and thirdly the pubis, which is the bone in [Pg 94] front of the acetabulum. The pubic bones meet in the middle line of the body on the under side of the pelvis in man, and on each side are partly separated from the ischia by a foramen, spoken of as the obturator foramen, which in Pterodactyles is minute and almost invisible, when it exists. ”

“ II. Ascomycetes.—This, except in the case of a few of the simpler forms, is a very sharply marked group characterized by a special type of sporangium, the ascus. In the development of the ascus we find two nuclei at the base which fuse together to form the single nucleus of the young ascus. The single nucleus divides by three successive divisions to form eight nuclei lying free in the protoplasm of the ascus. Then by a special method, described first by Harper, a mass of protoplasm is cut out round each nucleus; thus eight uninucleate ascospores are formed by free-cell formation. ”

“ The determination of the structure of the shoulder-girdle threw open the homology of this bone, which clearly could not be a clavicle, whatever else it might be. The alternative position once more lay in the pelvis, and this time between the ischium and the pubis; and as the ilium was bird-like, might not the ischium, or pubis, be also expected to be ornithic in form? At any rate the bone answered remarkably well to the ischium of one of the Ratitæ.
Resemblances to the structures found in some birds had already been noted by Prof. Owen [1] in the sacrum of the Dinosauria ”

“ Each half is firmly united to its fellow in a ventral symphysis behind, and is in front expanded and united to the sacrum. Each half or innominate bone is seen in the young animal to consist of four distinct parts, the ilium or dorsal element, the pubis or anterior ventral element, the ischium or posterior ventral element, and a small fourth part, the acetabular or cotyloid bone, wedged in between the three others. These parts, though all distinct in the young animal, are in the adult so completely fused that their respective boundaries cannot be distinguished. ”

“ But to name this great pelvic bone was a difficulty with me. I was under the impression that its broad, smoothly expanded surface might be best compared with that of an ischium [3] or pubis, and that this would be more suited to the broad depressed body (as I supposed it to be) of such a huge creature, than, by accepting it as an ilium, to admit the beast to have been narrow in the rear, like a bird, with the plane of the bone not much inclined from the vertical. ”

“ It has been known for half a century that the axone degenerates when cut off from the cell of which it is a process. The fact that the cell suffers also is a striking illustration of the essential unity of the nerve-cell and all its branches, whether they are long or short—three feet in length, as the axones that run from the lower part of the spinal cord to the foot may be, or a thousandth of an inch, like some which arise and terminate within the gray matter of the cord and brain. ”

“ The os innominatum has three primary centres for the ilium, ischium and pubis.
The special centres for the crest of the ilium are probably a serial repetition of those for the vertebral border of the scapula (see fig. 19) ; that for the anterior inferior spine is a purely human traction epiphysis connected with the use of the straight head of the rectus femoris in the upright position. The centre for the pubic symphysis probably represents the epipubis of amphibians, while that for the tuberosity of the ischium is the hypoischium of reptiles (see sub- section on comparative anatomy) . ”

“ The lateral ischiatic ridge is a relatively slight ridge continuous with the posterior end of the lateral iliac process and curves posteroventrally across the lateral surface of the posterior part of the ischium; the ridge extends to the ventral edge of the ischium in some individuals and not in others. The dorsolateral iliac ridge begins at the lateral edge of the ilium near the posterior end of the lateral iliac process and curves posteromedially and somewhat dorsally, extending to the posterior edge of the ilium. ”

“ The whole central marrow is merely a simple cylindrical cord which runs the length of the body, and ends equally simply at both extremities—a plain medullary tube. All that we can discover is a small vesicular bulb at the foremost part of the tube, a degenerate rudiment of a primitive brain. We meet the same simple medullary tube in the first structure of the ascidia larva, in the same characteristic position, above the chorda. On closer examination we find here also a small vesicular swelling at the fore end of the tube, the first trace of a differentiation of it into brain and spinal cord. ”

“ A left ischium is preserved only missing the articular surface of the iliac peduncle and pieces from the distal margin. The ischium is large and expanded ventrally into a broad relatively thin blade. The iliac peduncle is distinct from the neck leading to a large open acetabulum. In cross-section the iliac peduncle is ovoid with a constricted cranial margin, which extends into a sharp crest which borders the acetabular rim and joins the pubic peduncle. The pubic peduncle merges with the pubic articular surface and the distal articular surface into a single straight pubic articulation. ”

“ On reaching the part of the forest where I had, the day before, been chopping wood, I filled the cart with a heavy load, as a security against another runaway. But the neck of an ox is equal in strength to iron. It defies ordinary burdens. Tame and docile to a proverb, when well trained, when but half broken to the yoke, the ox is the most sullen and intractable of animals. I saw in my own situation several points of similarity with that of the oxen. They were property; so was I. Covey was to break me—I was to break them. ”

“ The General Mode of Slaughtering Oxen in this country is by striking them a smart blow with a hammer or poleaxe on the head, a little above the eyes. By this means, when the blow is skilfully given, the beast is brought down at one blow, and, to prevent recovery, a cane is generally inserted, by which the spinal cord is perforated, instantly depriving the ox of all sensation of pain. ”

“ The ax, which is not unlike a hay-knife, though much heavier and broader, is drawn up to the top of the posts, between which it runs in grooves, and is held suspended by a loop in the halyards, passed over a button at the bottom. The edge of the ax, as it hangs suspended, is not horizontal, or at a right angle with the post, but diagonal, giving the instrument a fearful power, in conjunction with its weight and long fall, of shearing through a resisting substance of many times more opposing force than a human neck. ”

“ These are the axons by which the muscles are aroused to activity. It is a general rule of the nervous system that no nerve cell extends without a break from any sense organ to any muscle fiber. The axon which communicates with the sense organ belongs to one nerve cell; the axon which connects with the muscle fiber belongs to a different nerve cell. The first is called a sensory nerve cell, the second a motor nerve cell. Some idea of the appearance of these cells can be gotten from the figures on page 126. ”

“ The pelvis is very strong; the broad pubes and ischia meet in the middle line, and they either enclose one wide undivided foramen, or the two symphysial portions meet, and there are then two obturator-foramina. The pubes are generally much larger, especially broader, than the ischia; and although partaking in the formation of the acetabulum, they do not articulate with the ilia, at least not in Plesiosauri. The ilia are always small; in Plesiosauri attached to only one or two sacral ribs; to three or four in the Triassic genera. ”

“ Slight changes in the shape of the body and a further growth and differentiation of the branchial sac, peribranchial cavity, and other organs now produce gradually the structure found in the adult Ascidian.
The most important points in connexion with this process of development and metamorphosis are the following. (1) In the Ascidian embryo all the more important organs (c.y., notochord, neural canal, archenteron) are formed in essentially the same i Some of the first test cells are also probably derived from the epithelium of the egg follicle. ”

“ There is no evidence that the cut end of a nerve can grow down and attach itself to a muscular or epithelial element without the assistance of a nerve tube down which to grow. When the cut nerves connected with the periphery degenerate, that applies only to the axis-cylinder and the medullary sheath, not to the neurilemma; the connective tissue elements remain alive and form a tube into which the growing axon finds its way, and so is conducted to the end-plate or end-organ of the peripheral structure. ”

“ The male and female axillae contain the same number and species of organs; and the difference by which the external configuration of both are marked mainly arises from the presence of the enlarged mammary gland, which, in the female, Plate 14, masks the natural outline of the pectoral muscle, E, whose axillary border is overhung by the gland ”

“ The pubes and ischia are fused along the mid-ventral line. Many morphologists regard, the ilium as equivalent to, that is, strictly corresponding in its relation, to the scapula, the pubis to the cartilaginous substratum of the clavicle, and the ischium to the coracoid.
Section 85. These bones will be studied at the greatest advantage when dissected out from a boiled rabbit. Prepared and wired skeletons, disarticulated skeletons, plates of figures, and written descriptions are in succession more tedious and less satisfactory ways to a real comprehension, of this matter. ”

“ It is so very slender that it cannot be seen except under a powerful microscope, and yet in our own bodies and the bodies of all large animals many of these are three feet or more in length without a break. This tiny protoplasmic thread, the axon, was formed originally by growing out from the cell body. As it grew it became surrounded by a sheath, which probably gives it strength and decreases the danger of its being broken. Another thing which helps to keep the axons from being injured is that they are always in bundles. ”

“ Special sense-organs are either wanting altogether or are only found in a very rudimentary form, as simple optic spots and touch-corpuscles or tentacles that surround the mouth. The muscular system is very slightly and irregularly developed. Immediately under the thin corium, and closely connected with it, we find a thin muscle tube, as in the worms. On the other hand, the Ascidia has a centralised heart, and in this respect it seems to be more advanced than the Amphioxus. On the ventral side of the gut, some distance behind the gill-crate, there is a spindle-shaped heart. ”