44 MICHIGAN ACADEMY OF SCIENCE. 



ever, the natural philosophy of the Greeks was wiped out under the 

 mental glaciers of the dark ages and prior to the time of Linna?us, the 

 origin and distribution of animal life was a closed book sealed 

 by ecclesiastical anathema to any one, who might have desired to read 

 therein. The doctrine of special creation, which was almost universally 

 accepted in the eighteenth century, was the necessary and inevitable 

 result of a prevalent and powerful theological scholasticism, which 

 pervaded and controlled all the great centers of intellectual life. 



To Linnreus and his school there were "as many species as issued 

 in pairs from the hands of the Creator." Specific creation was the 

 origin of all forms of life, and every species lived in the place appointed 

 for it by the wisdom of the Omnipotent. The termination of each of 

 the great geological epochs was signalized by a general massacre of all 

 existing forms of life, and the advent of the new era was signalized by the 

 creation of a new fauna specially adapted to the peculiar conditions of 

 the new world. 



To such a philosophy, "the structural relations found to exist between 

 the fossil forms themselves, and between the fossil and living forms are 

 meaningless and unimportant," and all speculations as to the reason for 

 the many apparent anomalies and excentricities found in the distribu- 

 tion of life at the present time are not only useless, but even blasphemous. 

 The publication of the "Origin of Species" in 1859 marked an epoch in 

 the intellectual history of the world. Whether the evolutionary theory 

 and the means by which it has operated be true or not, there can be 

 no question, but that its general acceptation as a working hypothesis 

 has done more to stimulate scientific work, and to increase the sum of 

 human knowledge than any other factor in the history of science. 



The adoption of the Darwinian postulates that "the several species of 

 the same genus, though now inhabiting the most distant quarters of 

 the world, must originally have preceded from the same source, as they 

 are descended from the same progenitor" and that "individuals of the 

 same species, though now inhabiting distant and isolated regions, must 

 have proceeded from one spot, where their parents were first produced." 

 necessarily involves the careful and systematic study of the distribution 

 of animal life from its earliest appearance to the present time. If the 

 theory of evolution be true, there must be an adequate explanation for 

 the present existence of every species where it is now found. In the 

 comparatively few years that have elapsed since this door of research 

 was opened, under the stimulating influences of the new doctrine, much 

 has been done in that direction. Indeed when it is considered that 

 successful investigation in this direction involves: 



1st. A comparative knowledge of the existing faunas of all the 

 different countries of the world. 



2d. A true and natural classification of the animal kingdom. 



3d. A consideration of the methods of dispersal and of the barriers 

 which prevent it; the effects of changes in physical geography and 

 climate and the various modes in which such changes affect the struc- 

 ture, distribution or the very existence of faunal life, and 



4th. As the existing distribution is the result and outcome of all 

 preceding changes of the earth and its inhabitants, a knowledge of the 

 animals of each country during past geological epochs, their migra- 



