Download or read book Contributions to Embryology, 1918, Vol. 8 written by Carnegie Institution of Washington and published by Forgotten Books. This book was released on 2016-11-26 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Contributions to Embryology, 1918, Vol. 8: Nos. 24, 25, 26 During the second developmental period the primordial blood-vessel plexus of the head slowly resolves itself into veins, arteries, and capillaries, and becomes architecturally suited to the circulatory ow of the blood. That portion Of the plexus which lies against the brain spreads out as a attened capillary sheet, con forming everywhere to the Shape of the brain-wall and its attached ganglia and sense-organs. The more superficial part of the plexus develops a coarser mesh and forms larger channels, which tend to unite into continuous trunks and gradually, by virtue Of their communications, can be recognized as definite arteries and veins. The intermediate loops of the plexus maintain the anastomosis between the deep capillary Sheet and the more superficial trunks, forming tributaries of the veins and branches of the arteries. The second period thus establishes the primary type of the circulation of the head, in which there is a capillary bed, fed by arterial branches from the aortic system and drained bilaterally by a continuous venous trunk which extends back to the venous end of the heart. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."