Despite creationist myth (propogated primarily by Jonathan Wells), Haeckel's embryonic sketches haven't been taken seriously for over a century and haven't appeared in any science textbook for just as long. If it weren't for young-Earth creationists, hardly anybody would know about Haeckel's embryonic sketches.
That is either ignorance or a lie.
Alton Biggs, Chris Kapicka, and Linda Lundgren, Biology: The Dynamics of Life (Westerville, OH: Glencoe/McGraw-Hill, 1998). ISBN 0-02-825431-7
Douglas J. Futuyma, Evolutionary Biology, Third Edition (Sunderland, MA: Sinauer Associates, 1998). ISBN 0-87893-189-9
Burton S. Guttman, Biology, (Boston: WCB/McGraw-Hill, 1999). ISBN 0-697-22366-3
George B. Johnson, Biology: Visualizing Life, Annotated Teacher's Edition (Orlando, FL: Holt, Rinehart & Winston, 1998). ISBN 0-03-016724-8
Kenneth R. Miller & Joseph Levine, Biology, Fifth Edition (Upper Saddle River, NJ: Prentice-Hall, 2000) ISBN 0-13-436265-9
Peter H. Raven & George B. Johnson, Biology, Fifth Edition (Boston: WCB/McGraw-Hill, 1999). ISBN 0-697-35353-2
William D. Schraer&HerbertJ. Stoltze, Biology: The Study of Life, Seventh Edition (Upper Saddle River, NJ: Prentice Hall, 1999). ISBN 0-13-435086-3
Cecie Starr & Ralph Taggart, Biology: The Unity and Diversity of Life, Eighth Edition (Belmont CA: Wadsworth Publishing Company, 1998). ISBN 0-534-53001-X
Each of these recently published texts "uses Haeckel's drawings (or a re-drawn version of them) without mentioning the dissimilarity of earlier stages; claims that early similarities in vertebrate embryos are evidence for common ancestry and Darwinian evolution; may call pharyngeal pouches 'gill slits.'"
information and quote taken from Icons of Evolution by Jonathan Wells. Regnary Publishing, 2000.
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edit: just found this on the web: http://www.txtwriter.com/Backgrounders/ ... age11.html
this doctor seems to consider the Haeckel ideas some of the strongest evidence for evolution!