22 HISTORICAL SKETCH 



In 1858 a celebrated geologist, Count Kejserling ("Bul- 

 letin do hi Soc. Gdolog.," 2il Scr., torn. x. page 857), 

 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 circumambient 

 molecules of a particular nature, and thus have given 

 rise to new forms. 



In this same year, 1853, Dr. Schaaffhausen published 

 an excellent pamphlet ("Verhand. des Naturhist. Vereins 

 der Preuss. Rlieinlands," etc.) in which he maintains the 

 development of organic forms on the earth. He infers 

 that many species have kept true for long periods, 

 whereas a few have become modified. The distinction 

 of species he explains by the destruction of intermediate 

 graduated forms. "Thus living plants and animals are 

 not separated from the extinct by new creations, but 

 are to be regarded as their descendants through contin- 

 ued reproduction." 



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

 1854 ("Etudes sur Geograph. Bot.," tom. i. page 250), 

 "On voit que nos recherches sur la fixitd ou la varia- 

 tion de I'esp^ce, nous conduisent directement aux id^es 

 ^mises, par deux hommes justement c^l^bres, GeoSroy 

 Saint-Hilaire et Goethe." Some other passages scattered 



b7 Oken in his mystical "Natur-Pbilosophie." From other references in 

 Godron's work "Sur I'Espece," it seems that Bory St. Vincent, Burdach, 

 Poiret, and Fries, have all admitted that new species are continually 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 acta 

 of creation, twenty -seven have written on special branches of natural history 

 or geology. 



I 



