404 A CENTURY OF SCIENCE 



pies here recognized. This remained for many years 

 the standard zoological and physiological text-book, and 

 was republished in several editions here and in England. 

 Another popular book is entitled "Methods of Study in 

 Natural History" (1864). 



More than 400 books and papers were written by 

 Agassiz, over a third of which were published before 

 he came to America. They cover both zoological and 

 geological topics, including systematic papers on living 

 and fossil groups of animals, but most important of all 

 are his philosophical essays on the general principles of 

 biology. 



One of Agassiz 's greatest services to zoology was the 

 publication of his " Bibliographia Zoologise et Geologise" 

 by the Ray Society, beginning with 1848. The publica- 

 tion of the Lowell lectures in Comparative Embryology 

 in 1849 gave wide audience to the general principles now 

 recognized in the biogenetic law of ancestral remin- 

 iscence. As stated in the Journal (8, 157, 1849), the 

 "object of the Lectures is to demonstrate that a natural 

 method of classifying the animal kingdom may be 

 attained by a comparison of the changes which are passed 

 through by different animals in the course of their devel- 

 opment from the egg to the perfect state; the change 

 they undergo being considered as a scale to appreciate 

 the relative position of the species." These "principles 

 of classification" are fully elucidated in a separate pam- 

 phlet, and are discussed at length in the Journal (11, 

 122, 1851). 



One of the most interesting of Agassiz 's numerous 

 philosophical essays, originally contributed to the Jour- 

 nal (9, 369, 1850), discusses the "Natural Relations 

 between Animals and the elements in which they live." 

 Another philosophical paper contributed to the Journal 

 discusses the "Primitive diversity and number of Ani- 

 mals in Geological times" (17, 309, 1854). Of his^sys- 

 tematic papers, those on the fishes of the Tennessee river, 

 describing many new species, were published in the Jour- 

 nal (17, 297, 353, 1854). 



Agassiz 's beautifully illustrated "Contributions to the 

 Natural History of the United States" cover many sub- 

 jects in morphology and embryology, which are treated 



