Ciup. I. 



IMMUTABILITY OF SPECIES. 



53 



favor of their mutability ; on tlic contrary, every modern investigation ^ has only 

 gone to confirm the results first obtained by Cuvier, and his views that species are 

 fixed. 



It is something to be able to show hy monumental evidence, and by direct com- 

 parison, that animals and plants have undergone no change for a period of about 

 five thousand years.' This result has had the greatest influence upon the progress 

 of science, especially with reference to the consequences to be drawni from the occiu"- 

 rence in the series of geological formations of organized beings as highly diversified 

 in each epoch as those of the present day ; ^ it has laid the foundation for the con- 

 viction, now imiversal among well infonned naturalists, that tliis globe has been in 

 existence for innumerable ages, and that the length of time elapsed since it first 

 became inhabited cannot be counted in years. Even the length of the period to 

 which we belong is still a problem, notwithstanding the precision with which certain 

 systems of chronology would fix the creation of man.* There are, however, many 

 circumstances which show that the animals now living have been for a much longer 

 period inhabitants of our globe than is generally supposed. It has been possible to 

 trace the formation and growth of our coral reefs, especially m Florida,^ with suffi- 

 cient precision to ascertain that it must take about eight thousand years for one of 

 those coral walls to rise from its foundation to the level of the surfiice of the ocean. 

 There are, aromid the southernmost exti'emity of Florida alone, four such reefs con- 

 centric with one another, which can be sho^vii to have grown uj?, one after the 

 other. This gives for the beginning of the first of these reefs an age of over thirty 

 thousand years; and yet the corals by which they were all built up are the same 

 identical species in aU of them. These facts, then, furnish as direct evidence as we 

 can obtain in any branch of physical inquiry, that some, at least, of the species of 

 animals now existing, have been in existence over thirty thousand years, and have 

 not inidergone the shghtest change during the whole of that period.® And yet these 



^ RuNTH, Rec'licrchcs sur les plantes frouvecs 

 dans U's tombeaux egyptiens, Ann. des seicii. nat., vol. 

 viii., 1826, p. 411. 



^ It is not for mc to discuss tlie degree of reli- 

 ability of the Egyptian chronology; but as far as it 

 goes, it shows that from tlic olihst jicriods ascer- 

 tained, animals have been what they are now. 



' See my paper upon The Primitive Diversity, 

 etc., quoted aljove, p. 25. 



* NoTT & Gliddon, Types of Mankind, p. C.')3. 



* See my paper upon the Reefs of Florida, soon 

 to be published in the Reports of the United States 



Coast Survey, extracts of wliich are already printed 

 ill the Report for 1851, p. 115. 



° Those who feel inclined to ascribe the differ- 

 ence's which exist between species of different geo- 

 logical periods to the modifying influence of physi- 

 cal agents, and who hiok to the changes now going 

 on among the living for the support of such an 

 o]iinion, and may not be satisfied that the facts just 

 mentioned are sufficient to prove the imnnitability 

 of species, but may still believe thai .t longer [icriod 

 of time would yet do what tliiily thousand years 

 have not done, I beg leave to refer, for further con- 



