""The Biological Problem of Today: Preformation or Epigenesis? The Basis of a Theory of Organic Development"" is a book written by Oscar Hertwig and published in 1896. The book explores the debate between preformation and epigenesis, two opposing theories on the origin and development of living organisms. Preformation suggests that all living beings are pre-formed in miniature, while epigenesis argues that organisms develop from an undifferentiated mass through a series of progressive changes. Hertwig presents his own theory of organic development, which combines elements of both preformation and epigenesis. He argues that the development of living beings is a complex process that involves both inherited traits and environmental factors. The book is considered an important contribution to the field of developmental biology and continues to be studied and referenced today.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.