2000, ISBN: 9780260907134

Hardback, [PU: Forgotten Books], Excerpt from International Congress of Arts and Science, Vol. 12: Medicine and Technology, Comprising Lectures on Obstetrics and Gynecology, Pediatrics, O… Plus…

Hardback, [PU: Forgotten Books], Excerpt from International Congress of Arts and Science, Vol. 12: Medicine and Technology, Comprising Lectures on Obstetrics and Gynecology, Pediatrics, Otology, Electrical and Mining Engineering, Civil and Mechanical Engineering, Technical Chemistry, and Agriculture In many countries the belief has long been current that the sex of the human fetus could be modified during a greater or less period of its uterine life. N ow we know that the sex is fixed at least by the beginning of the second month, for at that time the microscope can distinguish ovarian from testicular structure. It is, therefore, scarcely credible that any reversal of sex can be brought about after this period by any conceivable combination of influences. We must, indeed, look to conditions existing during the first month of gesta tion, or at the time of the meeting of spermatozoon and ovum, or to influences affecting either or both of the latter before conception, in order to find explanation of sex-determination in the human embryo. Those who believe that both sperm and ovum share in the production of sex refer to the various statistics giving the relationship of the parental ages to the sex of the offspring. Hofacker in 1823, and Sadler in 1830, independently stated, as the result of an analysis of about 2000 births, that when the father is the older the offspring are preponderatingly male; While if the parents be of the same age, or if the mother be older, there is a larger percentage of female children. This generalization, termed the law of Hofacker and Sadler, has been the subject of much debate, having been upheld by some and denied by others during the last 70 years. 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., Teaching Resources & Education, Teaching Resources & Education<