ZOOLOGY. 417 



stages of development ; " that in the lower grades of animal 

 and vegetable life they are so similar as to pass by insensi- 

 ble gradations into each other; and that in the higher forms, 

 while they diverge most widely in some of their aspects in 

 the bodies belonging to the two great kingdoms of organic 

 nature, and in the larger groups distinguishable within each 

 of them, yet it is still possible, from the fundamental similar- 

 ity of the phenomena, to trace in the transitional forms of all 

 their varieties one great general plan of organization." He 

 adds that, " if we admit the progressive nature of the changes 

 of development, their similarity in different groups, and their 

 common characters in all animals nay, even in some re- 

 spects in both plants and animals we can scarcely refuse to 

 recognize the possibility of continuous derivation in the his- 

 tory of their origin; and however far we may be, by reason 

 of the imperfection of our knowledge of paleontology, com- 

 parative anatomy, and embryology, from realizing the pre- 

 cise nature of the chain of connection by which the actual 

 descent has taken place, still there can be little doubt re-, 

 maining in the mind of any unprejudiced student of embry- 

 ology that it is only by the employment of such a hypoth- 

 esis as that of evolution that further investigation in these 

 several departments will be promoted so as to bring us to a 

 fuller comprehension of the most general law which regu- 

 lates the adaptation of structure to function in the universe." 

 In a richly illustrated volume on the embryology and anat- 

 omy of the starfish, Mr. Alexander Agassiz takes exception 

 to the prevailing Darwinian views in the following language: 

 " While," he says, "the successive appearance of the great 

 types of Echini in geological time in other words, their 

 paleontological development is in the strictest harmony 

 with what we know of their embryological development, we 

 as certainly know nothing whatever of the causes which have 

 brought about their sequence in time, in such striking agree- 

 ment with the sequence in their phases of growth. The case 

 of successive modifications of the ancestral horse, which has 

 so often been brought forward as conclusive re^ardins; the 

 genealogy of the group, although more familiar, is far less 

 complete and much more limited in time than the succession 

 to be traced from the paleontological evidence of Echini. 

 But, Avhile natural selection gives a plausible explanation of 



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