Atrium

“ This atrium, open as it was to the effects of the brilliant Egyptian atmosphere, offered a subtle psychic preparation for that elation of soul which stimulated the novitiate when, after ascending the steps on the far side of the atrium, he entered the sombre shadow of the hypostyle hall. This elation increased in many cases to a religious ecstasy when the novitiate ascended into the upper region where the esoteric mysteries were performed. ”

“ These first gill-slits in Amphioxus are later subdivided by the downgrowth of the tongue-bar from the dorsal edge.
Fig. 88.—Ventral aspect of three larvae of Amphioxus, showing the metapleural folds and the formation of the atrium. ap, Atriopore; k, gill-slits; lf and rf, left and right metapleural folds; m, mouth; w, pre-oral pit. (From Korschelt and Heider, after Lankester and Willey.)
The atrium is an ingrowth of the external space between the two ventral metapleural or atrial folds (Figs. 88 and 89) , paired lateral ridges of the body-wall, and so is lined by ectoderm. ”

“ The simple Roman house with its one large atrium, serving at once as kitchen, living room, and bed chamber, was completely transformed. The atrium became a pillared reception hall, special rooms were added for the various phases of domestic life; in the rear of the atrium arose a Greek peristyle courtyard, and the house was filled with costly sculptures and other works of art, plundered or purchased in the cities of Hellas. ”

“ The Roman house at first was extremely simple, being of but one room called the atrium, or darkened chamber, because its walls were stained by the smoke that rose from the fire upon the hearth and with difficulty found its way through a hole in the roof. The aperture also admitted light and rain, the water that dripped from the roof being caught in a cistern that was formed in the middle of the room. The atrium was entered by way of a vestibule open to the sky, in which the gentleman of the house put on his toga as he went out. ”

“ The reproductive organs (Figure 4, Sheet 20, g.) are masses of cells situated in an isolated part of the coelom in the atrial folds, and, having no ducts, their contents must escape into the atrium by rupture of the body-wall. Thence they escape either by gill-slits, pharynx and mouth, or, more generally, through the atrial pore. The animals, like all the vertebrata, are dioecious, i.e., male or female. ”

“ There is, as we shall see more clearly, a structure, the respiratory atrium, not apparently represented in the true vertebrate types, at least in their adult stages. There is no distinct heart, only a debateable brain, quite without the typical division into three primary vesicles, no skull, no structures whatever of cartilage or bone, no genital ducts, no kidneys at all resembling those of the vertebrata, no pancreas, no spleen ”

“ Their lintel beams should be placed high enough to make the height of the alae equal to their width.
5. The tablinum should be given two thirds of the width of the atrium when the latter is twenty feet wide. If it is from thirty to forty feet, let half the width of the atrium be devoted to the tablinum. When it is from forty to sixty feet, divide the width into five parts and let two of these be set apart for the tablinum. In the case of smaller atriums, the symmetrical proportions cannot be the same as in larger. ”

“ The several rooms to the left of the atrium offer nothing remarkable. On the right, however, as will be evident upon inspecting the plan, a suite of apartments existed, carefully detached from the remainder of the house, and communicating only with the atrium by a single passage. The disposition and the ornaments of this portion of the house prove that it was a private venereum, a place, if not consecrated to the goddess from whom it derives its name, at least especially devoted to her service. The strictest privacy has been studied in its arrangements; no building overlooks it ”

“ The heart consists of four parts, the sinus venosus, into which the veins enter, the auricle or atrium, the ventricle, and the arterial bulb at the base of the great artery which carries the blood to the gills. Of these parts the ventricle is deepest in color and with thickest walls. The arterial bulb varies greatly in structure, being in the sharks, rays, Ganoids, and Dipnoans muscular and provided with a large number of internal valves, and contracting rhythmically like the ventricle. ”

“ At the bottom of the hall were set out vases of Corinthian brass. This triclinium, the largest of four in the palace of Scaurus, would easily contain a table of sixty covers; [13] but he seldom brings together so large a number of guests, and when on great occasions he entertains four or five hundred persons, it is usually in the atrium. This eating-room is reserved for summer; he has others for spring, autumn, and winter, for the Romans turn the change of season into a source of luxury. ”

“ The primary and the secondary (or tongue-) bars can be distinguished from one another by their structure in the adult animal (Fig. 75, A and B) .
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Fig. 74.—Branchiostoma lanceolatum. A, transverse section of the pharyngeal region. a, Dorsal aorta; b, atrium; c, notochord; co, coelom; e, endostyle; g, gonad (ovary) ; kb, branchial septa; kd, pharynx; l, liver; my, myotome; n, nephridium; r, spinal cord; sn, sn, dorsal and ventral spinal nerves. B, Transverse section of the intestinal region. atr, Atrium; coel, coelom; d.ao, dorsal aorta; int, intestine; myom, myotome; nch, notochord ”

“ The heart has three cavities, and is situated above the lung at the division of the windpipe, and is provided with a fatty and thick membrane where it fastens on to the great vein and the aorta. It lies with its tapering portion upon the aorta, and this portion is similarly situated in relation to the chest in all animals that have a chest. In all animals alike, in those that have a chest and in those that have none, the apex of the heart points forwards, although this fact might possibly escape notice by a change of position under dissection. The rounded end of the heart is at the top. ”

“ Having tied the pulmonary artery, the pulmonary veins, and the aorta, in the body of a man who had been hanged, and then opened the left ventricle of the heart, we passed a tube through the vena cava into the right ventricle of the heart, and [231] having at the same time attached an ox’s bladder to the tube, in the same way as a clyster-bag is usually made, we filled it nearly full of warm water and forcibly injected the fluid into the heart, so that the greater part of a pound of water was thrown into the right auricle and ventricle. ”

“ From the left ventricle springs the largest arterial trunk in the body, over one-half of an inch in diameter, called the aorta. From the aorta other arteries branch off to carry the blood to all parts of the body, only to be again brought back by the veins to the right side, through the cavities of the ventricles. We shall learn in Chapter VIII. that the main object of pumping the blood into the lungs is to have it purified from certain waste matters which it has taken up in its course through the body, before it is again sent on its journey from the left ventricle. ”

“ The vascular system is very highly developed; the heart consists of a pair of auricles and a ventricle (figs. 12, 28) . Branchial hearts are formed on the afferent vessels of the branchiae. It is not known to what extent the minute subdivision of the arteries extends, or whether there is a true capillary system.
The pericardium is extended so as to form a very large sac, passing among the viscera dorsalwards and sometimes containing the ovary or testis—the viscero-pericardial sac—which opens to the exterior either directly or through the renal organs. ”

“ This septum aorticum (formed by two ingrowths from the wall of the vessel which fuse later) becomes twisted in such a way that the right ventricle is continuous with the last pair of aortic arches (pulmonary artery) , while the left ventricle communicates with the other arches (the permanent ventral aorta and its branches) ; it joins the septum ventriculorum in the upper part of the ventricular cavity and so forms the pars membranacea septi (fig. 3, T. Ar) .
The fate of the sinus venosus and auricle must now be followed. ”

“ The heart receives blood from the gills and mantle, and pumps it through arteries to the body. It consists of a median ventricle with muscular walls and a cavity traversed by muscular strands. On either side of the ventricle, in the primitive condition, is a thin-walled auricle, opening into the ventricle by a valved opening. Each auricle forms the terminal enlargement of the efferent vein of the ctenidium of its own side. In Nautilus two pairs of auricles are present, corresponding with the two pairs of ctenidia. ”

“ The muscular tissues of the heart were soft and tore easily. A few spots of fatty degeneration existed in the lining membrane of the aorta, just above the semilunar valves, and a slender clot of fibrine was found in the aorta, where it was divided, about two inches from these valves, for the removal of the heart. On the right side slight pleuritic adhesions existed between the convex surface of the lower lobe of the lung and the costal pleura, and firm adhesions between the anterior edge of the lower lobe, the pericardium and the diaphragm. ”

“ Whether the pericardium and the ventral sinus are made to expand simultaneously or all the movement is made by one only of the surfaces concerned, must depend on conditions of tension. In any case it is clear that we have in these muscles an apparatus for causing the blood to flow differentially in increased volume into either the pericardium, through the veins leading from the respiratory organs, or from the body generally into the great sinuses which bring the blood to the respiratory organs. ”