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The Universe No Desert, the Earth No Monopoly
The Universe No Desert the Earth No Monopoly Author:William Williams Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: VARIETY OF CUMULATIVE ORGANS. 13 through the under one. During its circuit, it escapes through the orifices, or the porous walls, into the tissues; and return... more »s to its regular channel, by means of the numerous openings at the sides, as is more concisely stated above. Some mollusks, as snails and muscles, have a heart with two cavities, an auricle and a ventricle. The circulating fluid passes from the former into the latter, whence it is distributed by arteries over the body ; then by veins to and through the respiratory organs, again to be poured into the auricle, with its appropriate valve. — The cuttlefish has two elementary cavities in addition, for propelling the fluid through the breathing apparatus.—A double muscular sac appears to be the simplest kind of heart in Nature, as it is found among the mollusks. And these differ from fishes only in one particular. The blood in the last traverses the gills before it reaches ths general circulation by means of the main artery. It is then returned to the auricle by the veins, and passes into and through the ventricle to the gills; thus permeating the heart but once in its round. — In the means of circulation, lobsters and crustaceans, generally, are inferior to some mollusks. They have no auricle, and but one ventricle.— Sea-urchins exhibit a tubular heart. Reptiles have three cavities, — two auricles and one ventricle. One auricle receives the blood from the lungs. The other receives it from the system. Both pour their mingled contents into the ventricle, whence it issues through two arteries into the general circulation and into the lungs. Among Crocodiles, is a still higher organization. They have two separate ventricles, though the great arteries, at their bases, have a partial communication with each other, and the two k...« less