LINNZUS AND NATURAL HISTORY 137 
divisions—branches, subkingdoms, or phyla—which, with 
small modifications, are still in use. These are Protozoa, 
Ccelenterata, 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 
Siebold 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 
Linneus. We may speak of the latter two as the founders 
of systematic botany and zodlogy. But the system left by 
Linnzus 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 Siebold 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 Linneus, Cuvier, Von Siebold, and 
Letckart 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 
