230 LOUIS AGASSIZ. [CHAP. ix. 



safe guide to the laws of development of organized 

 beings, and that we must be on our guard against all 

 those systems of transformation of species so lightly 

 invented by the imagination." What a prophetic and 

 true sentence against Darwin's " Origin of Species," 

 published fifteen years after. Observations and facts 

 only are given in his " Old Red Fishes," which he has 

 well summarized in the following words : " What I wish 

 to prove here, by a careful discussion of the facts 

 reported in the following pages, is the truth of the law 

 now so clearly demonstrated in the series of verte- 

 brates, that the successive creations have undergone 

 phases of development analogous to those of the embryo 

 in its growth, and similar to the gradations shown by 

 the present creation in the ascending series, which it 

 presents as a whole. One may consider it as hence- 

 forth proved that the embryo of the fish during its 

 development, the class of fishes as it at present exists 

 in its numerous families, and the type of fishes in its 

 planetary history, exhibit analogous phases through 

 which one may follow the same creative thought like a 

 guiding thread in the study of the connection between 

 organized being. . . . The facts, taken as a whole, 

 seem to me to show, not only that the fishes of the Old 

 Red constitute an independent fauna, distinct from those 

 of other deposits, but that they also present in their 

 organization the most remarkable analogy with the first 

 phases of embryologic development in the bony fishes 

 of our epoch, and a no less marked parallelism with the 

 lower degrees of certain types of the class as it now 

 exists on the surface of the earth." 



