HISTORICAL SKETCH. 



de sa destinee dans l'ordre de choses dont il fait partie. C'est cette 

 puissance qui harmonise chaque membre a l'ensemble en l'appro- 

 priant a la fonction qu'il doit remplir dans l'organisme general de 

 la nature, fonction qui est pour lui sa raison d'etre." * 



In 1853 a celebrated geologist, Count Keyserling ('Bulletin do 

 la Soc. Geolog.,' 2nd Ser., torn. x. p. 357), suggested that as new 

 diseases, supposed to have been caused by some miasma, have 

 arisen and spread over the world, so at certain periods the germs 

 of existing species may have been chemically affected by circum- 

 ambient molecules of a particular nature, and thus have given 

 rise to new forms. 



In this same year, 1853, Dr. Schaaffhausen published an ex- 

 cellent pamphlet ('Verhand. des Naturhist. Vereins der Preuss. 

 Piheinlands,' &c), in which he maintains the progressive develop- 

 ment of organic forms on the earth. He infers that many species 

 have kept true for long periods, whereas a few have become modi- 

 fied. The distinction of species he explains by the destruction 

 of intermediate graduated forms. " Thus hiving plants and animals 

 are not separated from the extinct by new creations, but are to 

 be regarded as their descendants through continued reproduction." 



A well-known French botanist, M. Lecoq, writes in 1854 

 (' Etudes sur Geograph. Bot.,' torn. i. p. 250), " On voit que nos 

 recherches sur la fixite" ou la variation de l'espe*ce, nous conduisent 

 directement aux ide'es dmises, par deux hommes justement celebres, 

 Geoffroy Saint-Hilaire et Goethe." Some other passages scattered 

 through M. Lecoq's large work, make it a little doubtful how far he 

 extends his views on the modification of species. 



The ' Philosophy of Creation ' has been treated in a masterly 

 manner by the Kev. Baden Powell, in his ' Essays on the Unity of 

 Worlds,' 1S55. Nothing can be more striking than the manner in 

 which he shows that the introduction of new species is " a regular, 



* From references in Bronn's ' Untersuchungen fiber die Entwickelungs- 

 Gesetze,' it appears that the celebrated botanist and pala:ontologist Unger 

 published, in 1852, his belief that species undergo development and modifi- 

 cation. D'Alton, likewise, in Pander and Dalton's work on Fossil Sloths, 

 expressed, in 1821, a similar belief. Similar views have, as is well known, 

 been maintained by Oken in his mystical ' Natur-Philosophie.' From other 

 references in Godron's work ' Sur l'Espece,' it seems that Bory St. Vincent, 

 Burdach,Poiret, and Fries, have all admitted that new species are continu- 

 ally being produced. 



I may add, that of the thirty-four authors named in this Historical 

 Sketch, who believe in the modification of species, or at least disbelieve in 

 separate acts of creation, twenty-seven have written on special branches or 

 natural history or geology. 



