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 was out.— The Bookseller said he had not read it but had heard it was a very remarkable book!!!" In December 1859 the botanist Asa Gray negotiated with a Boston publisher for publication of an authorised American version, however, he learnt that two New York publishing firms were already planning to exploit the absence of international copyright to print "Origin". Darwin wrote in January, "I never dreamed of my Book being so successful with general readers: I believe I should have laughed at the idea of sending the sheets to America." and asked Gray to keep any profits. Gray managed