http://book.klll.cc/ebooks/author/38711.opds?sort_order=release_date 2025-11-18T05:38:56Z Books by Hertwig, Oscar Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-11-18T05:38:56Z https://en.wikipedia.org/wiki/Oskar_Hertwig See also: en.wikipedia 2025-11-18T05:38:56Z https://book.klll.cc/ebooks/37221.opds The Biological Problem of To-day: Preformation Or Epigenesis? Oscar Hertwig