On the Origin of Species Darwin's ideas with those of Lamarck and Goethe while still reflecting the spirit of "Naturphilosophie". Their ambitious programme to reconstruct the evolutionary history of life was joined by Huxley and supported by discoveries in palaeontology. Haeckel used embryology extensively in his recapitulation theory, which embodied a progressive, almost linear model of evolution. Darwin was cautious about such histories, and had already noted that von Baer's laws of embryology supported his idea of complex branching. Asa Gray promoted and defended "Origin" against those American naturalists with an idealist approach, notably Louis Agassiz who viewed every species as a distinct fixed unit
Reactions to On the Origin of Species example and Ramsay's data in chapter 9 of "On the Origin of Species" to estimate that erosion of the Weald's layered dome of Lower Cretaceous rocks “must have required 306,662,400 years; or say three hundred million years“. The "necessary corrections" Darwin made to his drafts for the second edition of the "Origin" were based on comments from others, particularly Lyell, and added a caveat suggesting a faster rate of erosion of the Weald: "perhaps it would be safer to allow two or three inches per century, and this would reduce the number of years to one hundred and fifty or