220 ESSAY ON CLASSIFICATION. Part I. 



The writer who can see that the Quadrupeds unite with the Fishes, and the 

 like, and yet says that Cuvier "was totally unacquainted with the very first princi- 

 ples of the natural system," hardly deserves to be studied in our days. 



The attempt at representing graphically the complicated relations which exist 

 among animals has, however, had one good result; it has checked, more and more, 

 the confidence in the uniserial arrangement of animals, and led to the construction 

 of many valuable maps exhibiting the multifarious relations which natural groups, 

 of any rank, bear to one another. 



SECTION VI. 



EMBRYOLOGICAL SYSTEMS. 



Embryology, in the form it has assumed within the last fifty years, is as 

 completely a German science as the " Naturphilosophie." It awoke to this new 

 activity contemporaneously with the development of the Philosophy of Nature. It 

 would hardly be possible to recognize the leading spirit in this new development, 

 from his published works ; but the man whom Pander and K. E. von Baer 

 acknowledge as their master must be considered as the soul of this movement, 

 and this man is Ignatius DiiUinger. It is with deep gratitude I remember, for 

 my own part, the influence that learned and benevolent man had upon my studies 

 and early scientific application, during the four years I spent in his house, in 

 Munich, from 1827 to 1831 ; to him I am indebted for an acquaintance with what 

 was then known of the development of animals, prior to the publication of the 

 great work of Baer; and from his lectures I first learned to appreciate the im- 

 portance of Embryology to Physiology and Zoology. The investigations of Pander^ 

 upon the development of the chicken in the egg, which have opened the series 

 of those truly original researches in Embryology of which Germany may justly 

 be proud, were made under the direction and with the cooperation of Dollinger, 

 and were soon followed by the more extensive works of Rathke and Baer, whom 

 the civilized world acknowledges as the founders of modern Embryology. 



The principles of classification joropounded by K. E. von Baer seem never to 

 have been noticed by systematic writers, and yet they not only deserve the most 

 careful consideration, but it may fairly be said that no naturalist besides Cuvier 

 has exhibited so deep an insight into the true character of a natural system, 



^ Pander, Beitriige zur Entwickelungsgeschichte des Hiihnchens im Eie, Wurzburg, 1817, 1 vol. fol. 



