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PLACENTA (Lat. for a cake)

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Originally appearing in Volume V21, Page 691 of the 1911 Encyclopedia Britannica.
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See also:

PLACENTA (See also:Lat. for a cake)  , in See also:anatomy, the See also:organ by which the embryo is nourished within the womb of its See also:mother . When the See also:young one is See also:born the See also:placenta and membranes come away as the " afterbirth." Inhuman anatomy the organ is a circular disk about seven or eight inches in See also:diameter and one and a See also:quarter inches in thickness at its centre, while at its margin it is very thin and is continuous with the foetal membranes . It weighs about a See also:pound . In See also:order to explain the formation of the placenta it is necessary to encroach to some extent on the domain of See also:physiology . Before each menstrual See also:period, during the See also:child-bearing See also:age of a woman, the mucous membrane of the uterus hypertrophies, and, at the period, is See also:cast off and renewed, but if a fertilized ovum reaches the uterus the casting off is postponed until the See also:birth of the child . From the fact that the thickened mucous membrane lining the interior of the uterus is cast off sooner or later, it is spoken of as the " decidua." The fertilized ovum, on reaching the uterus, sinks into and embeds itself in the already prepared decidua, and, as it enlarges, there is one See also:part of the decidua lying between it and the uterine See also:wall (" decidua serrotina " or " basalis "), one part stretched over the See also:surface of the enlarging ovum (" decidua reflexa " or " capsularis ") and one part lining the See also:rest of the uterus (" decidua See also:vera ") (see fig I.) . Decidua basalis . under Alonzo de Ojeda, by whom he was entrusted with the See also:charge of the unfortunate See also:settlement at See also:San See also:Sebastian . He accompanied See also:Balboa (whom he afterwards helped to bring to the See also:block) in the See also:discovery of the Pacific; and under Pedrarias d'See also:Avila he received a repartimento, and became a See also:cattle-See also:farmer at See also:Panama . Here in 1522 he entered into a See also:partnership with a See also:priest named Hernando de Luque, and a soldier named Diego de See also:Almagro, for purposes of exploration and See also:conquest towards the See also:south . See also:Pizarro, Almagro and Luque afterwards renewed their compact in a more See also:solemn and explicit manner, agreeing to conquer and See also:divide equally among themselves the opulent See also:empire they hoped to reach . Explorations were then undertaken down the See also:west See also:coast of South See also:America, in which Pizarro, though See also:left. for months with but thirteen followers on a small See also:island without See also:ship or stores, persisted till he had coasted as far as about 9° S. and obtained distinct accounts of the Peruvian Empire .

The See also:

governor of Panama showing little disposition to encourage the adventurers, Pizarro resolved to apply to the See also:sovereign in See also:person for help, and with this See also:object sailed from Panama for See also:Spain in the See also:spring of 1528, reaching See also:Seville in See also:early summer . See also:Charles V. was won over, and on the 26th of See also:July 1529 was executed at See also:Toledo the famous See also:capitulation, by which Pizarro was upon certain conditions made governor and See also:captain-See also:general of the See also:province of New See also:Castile for the distance of 200 leagues along the newly discovered coast, and invested with all the authority and prerogatives of a See also:viceroy, his associates being left in wholly secondary positions . One of the conditions of the See also:grant was that within six months Pizarro should raise a sufficiently equipped force of two See also:hundred and fifty men, of whom one hundred might be See also:drawn from the colonies; as he could not make up his due See also:complement he sailed clandestinely from San Lucar in See also:January Glam.{ Dilated Part . 1530 . He was afterwards joined by his See also:brother Unchanged part . Hernando with the remaining vessels, and when the expedition left Panama in January of the following See also:year it numbered three See also:ships, one hundred and eighty men, and twenty-seven horses . The subsequent movements of Pizarro belong to the See also:history of See also:Peru (q.v.) . After the final effort of the Incas to recover See also:Cuzco in 1J36-37 had been defeated by Diego de Almagro, a dispute occurred between him and Pizarro respecting the limits of their See also:jurisdiction . This led to See also:battle; Almagro was defeated (1538) and executed; but his supporters conspired, and assassinated Pizarro on the 26th of See also:June 1541 .

End of Article: PLACENTA (Lat. for a cake)
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