Haeckel ’ s illustrations show vertebrate embryos at different stages of development, which exhibit embryonic resemblance as support for evolution, recapitulation as evidence of the Biogenetic Law, and phenotypic divergence as evidence of von Baer ’ s laws.

In the case of echinoderms, he argued that the bilateral larvae must have been introduced after the establishment of the existing classes, and he challenged Haeckel ’ s view that these larvae are evidence that echinoderms evolved from bilateral ancestors.

" He sometimes retorted sharply, " I am sorry to have to inform you that I do not believe in the Bible as a divine revelation, & therefore not in Jesus Christ as the Son of God ", and at other times was more guarded, telling a young count studying with Haeckel that " Science has nothing to do with Christ ; except in so far as the habit of scientific research makes a man cautious in admitting evidence.

This is the idea propagated by Ernst Haeckel as a source of evolutionary evidence ( recapitulation theory ).

Recent molecular and morphologic data add increasing evidence against this view, and the alternative colonial theory, also proposed by Haeckel in the 1870s is gaining widespread acceptance.

Ernst Haeckel claimed that Negroes have stronger and more freely movable toes than any other race which is evidence that Negroes are connected to apes because when apes stop climbing in trees they hold on to the trees with their toes, Haeckel compared Negroes to “ four-handed ” apes.

His, in opposition to Haeckel, seeks to take human embryos out of the hands of Darwinist proponents.

Although Haeckel is proven right about the allantois, the utilization of Krause ’ s embryo as justification turns out to be problematic, for the embryo is that of a bird rather than a human.

His also accuses Haeckel of creating early human embryos that he conjured in his imagination rather than obtained through empirical observation.

Nevertheless, Bischoff ’ s main argument was in reference to Haeckel ’ s drawings of human embryos, for Haeckel is later accused of miscopying the dog embryo from him.

For Haeckel, language specifically represented the concept that all phenomena of human development relate to the laws of biology.

For example, Haeckel proposed that the pharyngeal grooves between the pharyngeal arches in the neck of the human embryo resembled gill slits of fish, thus representing an adult " fishlike " developmental stage as well as signifying a fishlike ancestor.

Nevertheless, his chief interest was in human evolution, influenced by Ernst Haeckel, who reasoned that there must be intermediate species between apes and human.

The presence of gill-like slits in the neck of the developing human embryo famously led Ernst Haeckel to postulate that " ontogeny recapitulates phylogeny "; this hypothesis, while false, contains elements of truth, as explored by Stephen Jay Gould in Ontogeny and Phylogeny.

Haeckel divided human beings into ten races, of which the Caucasian was the highest and the primitives were doomed to extinction.

As a philosopher, Ernst Haeckel wrote Die Welträtsel ( 1895 – 1899, in English, The Riddle of the Universe, 1901 ), the genesis for the term " world riddle " ( Welträtsel ); and Freedom in Science and Teaching to support teaching evolution.

Haeckel introduced the concept of " heterochrony ", which is the change in timing of embryonic development over the course of evolution.

Ernst Haeckel, along with Karl von Baer and Wilhelm His, are primarily influential in forming the preliminary foundations of ‘ phylogenetic embryology ’ based on principles of evolution.

The term, ‘ recapitulation ,’ has come to embody Haeckel ’ s Biogenetic Law, for embryonic development is a recapitulation of evolution.

" Haeckel ’ s ABC of evolution and development.

While often seen as rejecting Darwin's theory of branching evolution for a more linear Lamarckian " biogenic law " of progressive evolution, this is not accurate: Haeckel used the Lamarckian picture to describe the ontogenic and phylogenic history of the individual species, but agreed with Darwin about the branching nature of all species from one, or a few, original ancestors.

Haeckel used embryology extensively in his recapitulation theory, which embodied a progressive, almost linear model of evolution.

Historians write that most such political and economic commentators had only a superficial understanding of Darwin's scientific theory, and were as strongly influenced by other concepts about social progress and evolution, such as the Lamarckian ideas of Spencer and Haeckel, as they were by Darwin's work.

Ernst Haeckel ( 1866 ), in his endeavour to produce a synthesis of Darwin's theory with Lamarckism and Naturphilosophie, proposed that " ontogeny recapitulates phylogeny ," that is, the development of the embryo of every species ( ontogeny ) fully repeats the evolutionary development of that species ( phylogeny ), in Geoffroy's linear model rather than Darwin's idea of branching evolution.

Lamarckism also appealed to those, like the philosopher Herbert Spencer and the German anatomist Ernst Haeckel, who saw evolution as an inherently progressive process.

* Konrad Körner: Linguistics and evolution theory ( Three essays by August Schleicher, Ernst Haeckel and Wilhelm Bleek ).

Ernst Haeckel ( 1834 – 1919 ) became famous for his " recapitulation theory ", according to which each individual mirrors the evolution of the whole species during his life.

Early twentieth-century biologists like Ernst Haeckel viewed embryology as a recapitulation of evolution, which implies a kind of organising memory, and a few modern biologists, such as Rupert Sheldrake, influenced by Jungian ideas and by vitalism, have posited organising fields of life consisting of memories and drives.

As a professor of anatomy at the University of Jena ( 1855 – 1873 ) and at the University of Heidelberg ( 1873 – 1903 ), Carl Gegenbaur was a strong supporter of Charles Darwin's theory of organic evolution, having taught and worked, beginning in 1858, with Ernst Haeckel, 8 years his junior.

Admiring visitors included Ernst Haeckel, a zealous follower of Darwinismus in a translation favouring progressive evolution over natural selection.

In response to Haeckel ’ s evolutionary claim that all vertebrates are essentially identical in the first month of embryonic life as proof of common descent, His responds by insisting that a more skilled observer would recognize even sooner that early embryos can be distinguished.

In fact, ontogeny evolves – the phylogenetic history of a species cannot be read directly from its ontogeny, as Haeckel thought would be possible, but characters from ontogeny can be ( and have been ) used as data for phylogenetic analyses ; the more closely related two species are, the more apomorphies their embryos share.

Later, the German morphologist Ernst Haeckel would convince Huxley that comparative anatomy and palaeontology could be used to reconstruct evolutionary genealogies.

Similarities can be seen along the first two rows ; the appearance of specialized characters in each species can be seen in the columns and a diagonal interpretation leads one to Haeckel ’ s idea of recapitulation.

Some version of Haeckel ’ s drawings can be found in many modern biology textbooks in discussions of the history of embryology, with clarification that these are no longer considered valid.

In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, and that reptiles, birds and mammals were united by the amniotic egg.

This important refutation of both preformation and the mosaic theory of Wilhelm Roux was to be subject to much discussion in the ensuing years, and caused friction among Driesch, Roux and Haeckel.

The complete phrase " argument from poor design " has rarely been used in the literature, but arguments of this type have appeared many times, sometimes referring to poor design, in other cases to suboptimal design, unintelligent design, or dysteleology ; the last is a term applied by the nineteenth-century biologist Ernst Haeckel to the implications of organs so rudimentary as to be useless to the life of an organism (, p. 331 ).

In what was to be the last decade of his life, he penned works such as Parsifal Unveiled, which details the esoteric symbolism of the Wagner opera, and Gnostic Anthropology in which he heavily criticizes the theories of Darwin, Haeckel, " and their followers ".

For example, Haeckel described and named hypothetical ancestral microorganisms that have never been found.

Haeckel ’ s opponents found his methods problematic because such simplification eliminates certain structures that differentiate between higher and lower vertebrates.