LINN^US AND NATURAL HISTORY 137 



divisions— branches, subkingdoms, or phyla — which, with 

 small modifications, are still in use. These are Protozoa, 

 Coelenterata, Echinoderma, Vermes, Arthropoda, Mollusca, 

 Vertebrata. These seven phyla are not entirely satisfactory, 

 and there is being carried on a redistribution of forms, as in 

 the case of the brachiopods, the sponges, the tunicates, etc. 

 While all this makes toward progress, the changes are of 

 more narrow compass than those alterations due to Von 

 Sieboid and Leuckart. 



Summary. — In reviewing the rise of scientific natural 

 history, we observe a steady development from the time of 

 the Physiologus, first through a return to Aristotle, and 

 through gradual additions to his observations, notably by 

 Gesner, and then the striking improvements due to Ray and 

 Linnaeus. We may speak of the latter two as the founders 

 of systematic botany and zoology. But the system left by 

 Linnaeus was artificial, and the greatest obvious need was to 

 convert it into a natural system founded upon a knowledge 

 of the structure and the development of living organisms. 

 This was begun by Cuvier and Von Baer, and was continued 

 especially by Von Sieboid and Leuckart. To this has been 

 added the study of habits, breeding, and adaptations of or- 

 ganisms, a study which has given to natural history much 

 greater importance than if it stood merely for the systematic 

 classification of animals and plants. 



Tabular View of Classifications. — A table showing the 

 primary groups of Linnaeus, Cuvier, Von Sieboid, and 

 Leuckart will be helpful in picturing to the mind the modifi- 

 cations made in the classification of animals. Such a table 

 is given on the following page. 



L. Agassiz, in his famous essay on Classification, reviews 

 in the most scholarly way the various systems of classifica- 

 tion. One peculiar feature of Agassiz's philosophy was his 

 adherence to the dogma of the fixity of species. The same 



