EMBRYONIC FOKMS. 227 



periods, come to a high state of advancement in art, govern- 

 ment, and social refinement, which were again succeeded by 

 universal ignorance and barbarism we are not to consider 

 these examples as contradicting the doctrine of progression, 

 as a general principle, but as only the particular and local ex- 

 ceptions to the direct development of that piinciple in outer 

 forms. 



Keeping in view, then, the doctrine of general Progression 

 as an undeniable principle applicable to the universal series 

 of creation as a whole, and to all its included and correspond- 

 ing sub- series, we are prepared for further inquiries respecting 

 the order and method of progression, and the mutual relations 

 of the different parts or degrees of each series of creation to 

 which this principle applies. In making these inquiries, our 

 attention will be confined for the present to the Animal King- 

 dom, which will serve as a representative of all other serial 

 creations. 



The fact alluded to by the author of the " Vestiges of Crea- 

 tion," that in the reproduction of the higher animals and of 

 man, the embryo passes through successive stages of develop- 

 ment, in which the types of all the lower animals, beginning 

 with the fish (or, as some say, with the annalid or worm), are 

 represented in succession, until its own proper type is attained, 

 is certainly of great significance, as it bears upon the subject 

 under consideration. But Professor Agassiz has made some 

 further discoveries in the department of embryology, which 

 would perhaps go to emphasize the conclusions to which this 

 fact would seem naturally to point. I would refer now par- 

 ticularly to the discovery that the embryos of animals of cer- 

 tain existing families bear, at a certain stage of their foetal 

 progress, a distinct resemblance to the perfected individuals 

 of now extinct species of the same families, which existed in 



