318 PROCEEDINGS OP THE AMERICAN ACADEMY 



which were included monographs of the CtenophorjB, Discophorae, 

 and Hydroidse, and an essay on the homologies of the Radiata. 

 His chief assistant in their preparation was the late Professor H. J. 

 Clark. They were illustrated by lithographic plates, which have never 

 been surpassed in excellence, and the best of which were drawn by 

 "Sonrel. 



The " Essay on Classification " is the flower of the mature thought 

 of Agassiz. In it may be discovered the elaboration of ideas which are 

 scattered through his earlier productions. To properly appreciate this 

 masterly disquisition, it must be remembered that Agassiz had always a 

 metaphysical mind, and one in which the idea of intelligent power was 

 a ground principle. Although he had not accepted the results of 

 Oken, he heartily admired his spirit, and ever spoke of him with pleas- 

 ure.* Indeed, he may be said to have adopted the method of Cuvier 

 and the inspiration of Oken. Advancing from this point, Agassiz inter- 

 prets the phenomena of Not-self by those of Self. The last paper that 

 came from his hand, " Evolution and Permanence of Type," has this 

 sentence : " It cannot be too soon understood that Science is one ; and 

 that, xohether we investigate language, philosophy, theology, history, 

 or physics, we are dealing with the same problem, culminating in the 

 knowledge of ourselves." The human mind is for him an entity in 

 accord with the Creating Spirit, and capable therefore of studying and 

 appreciating creation. This study and this appreciation he considers 

 Science ; and he finds in the animal kingdom the physical expression of 

 various intellectual operations, some sharply defined and some shadowy, 

 some simple and some hopelessly complex, just as are the familiar 

 workings of the human mind. Not only is his erudition throughout 

 remarkable, but his grasp of facts, intricate in their relations and 

 numerous, is quite amazing. In nothing is this better exhibited than 

 in his celebrated demonstration of the correspondence of embryological, 

 geological, and zoological succession. He shows that, in many orders, 

 the Sjiecies which first appear in the older beds resemble the embryo of 

 the highest species now living ; and, moreover, that this fossil and this 

 embryo have characters in common with the living species that stand 

 lower in the zoological scale. Thus among Crustacea the living 

 Brachyurans stand highest ; but the embryo of the Brachyuran has a 

 long tail like the Macrourans, which are characteristic of the middle 

 geological periods, and among the living are zoologically inferior to the 

 Brachyurans. 



* Essay on Classification, p. 336. 



