I. Haeckel and His Opponents

[^2]: Fundamental Biogenetic Law. Haeckel has proved in a series of works the general validity and far-reaching significance of the fundamental biogenetic law. The most important explanations and proofs will be found in his Biology of the Corals (1872) and in his Studies in the Gastrula Theory (1873–84). Since then other zoologists have extended and confirmed this doctrine. In his latest work, Die Welträtsel (1899), Haeckel is able to say of it (p. 72): “Although this doctrine was at the outset almost generally rejected, and for some ten years fiercely combated by numerous authorities, yet, at the present time (for about fifteen years past), it has been accepted by all well-informed specialists in the subject.”