02881cam a22003493u 450000100060000000300070000600500170001300600020003000700050003200800410003704000110007804100170008905000070010610000310011324000430014424501140018724601100030126400510041130000470046233600260050933700260053533800360056150000310059750802180062852014820084653400450232865300260237365300150239965300130241470000610242785600430248837221UtSlPG20260610133840.0mcr n260607r2011||||utu|||||o|||||||||||||| d  aUtSlPG 7aen2iso639-1 4aQH1 aHertwig, Oscar,d1849-192210aPräformation oder Epigenese? English14aThe Biological Problem of To-day: Preformation Or Epigenesis? :bThe Basis of a Theory of Organic Development1 aThe Biological Problem of Today: Preformation Or Epigenesis?
The Basis of a Theory of Organic Development 1aSalt Lake City, UT :bProject Gutenberg,c2011  a1 online resource :bmultiple file formats  atextbtxt2rdacontent  acomputerbc2rdamedia  aonline resourcebcr2rdacarrier  aRelease date is 2011-08-27  aProduced by Bryan Ness, Josephine Paolucci and the Online
Distributed Proofreading Team at http://www.pgdp.net. (This
book was produced from scanned images of public domain
material from the Google Print project.)  a"The Biological Problem of To-day: Preformation Or Epigenesis?" by Oscar Hertwig is a scientific treatise written in the late 19th century. This work delves into the biological debate concerning the nature of development, specifically examining two opposing theories: preformation, which posits that all characteristics of an organism are already present in a miniature form within the germ, and epigenesis, which suggests that development is a progressive formation from an initially unorganized state. Hertwig's exploration of these theories is informed by his expertise in embryology and cell biology.  The opening of the book sets up the central question regarding whether embryonic development represents a preformed structure or an elaborative process shaped by environmental influences. Hertwig introduces the ideas of other biologists, particularly focusing on August Weismann's germplasm theory, which classifies hereditary material as distinct and stable while addressing the complexities of reproduction and differentiation. Through critical analysis, Hertwig aims to establish that true development relies on epigenesis, where the organism grows and develops through interactions with its surroundings, rather than merely revealing what was predetermined in the germ. The opening serves as a prelude to a deeper examination of the implications each theory carries for understanding heredity and the intricacies of life. (This is an automatically generated summary.)  nOriginal publication data not identified  aDevelopmental biology  aEmbryology  aGenetics1 aMitchell, P. Chalmers, Sirq(Peter Chalmers),d1864-194540uhttps://www.gutenberg.org/ebooks/37221