Biogenetic law was formulated by Ernst Haeckel in 1866. The law states that “an organism passes through successive Stages resembling the series of ancestral type from which it has descended so that the ontogeny of the individual is a recapitulation of the phylogeny of the group”. That means an organism passes through its life stages it shows the similar appearance of the ancestor from which it has given birth so the individuals ontogeny is the repetition of the phylogeny of the group. This law is also known as “Recapitulation Theory”.
The biogenetic law is a theory of development and evolution proposed by Ernst Haeckel in Germany in the 1860s. It is one of several recapitulation theories, which posit that the stages of development for an animal embryo are the same as other animals’ adult stages or forms.
Biogenetic law, also called Recapitulation Theory, postulation, by Ernst Haeckel in 1866, that ontogeny recapitulates phylogeny—i.e., the development of the animal embryo and young traces the evolutionary development of the species. The theory was influential and much-popularized earlier but has been of little significance in elucidating either evolution or embryonic growth.