40 KAMBLES OP A NATURALIST. 



thought that they were to be sought exclusively in 

 the organisation of adult animals, and more especially 

 in the nervous system, and in this respect he departed 

 from the principle that had been established by the 

 genius of Jussieu, who sought in the embryo itself 

 the primordial divisions of the vegetable kingdom. 

 Zoology is only now beginning to enter upon that 

 course of inquiry which- has been so long and 

 steadily pursued by botany, and it at length turns 

 to embryology, which has already furnished it with 

 more than one satisfactory reply both in respect to 

 the present and the future. 



Milne Edwards was one of the first to enter upon 

 this new line of investigation *, and, as early as 

 1833, on presenting to the Academy a memoir re- 

 lating to the changes of form experienced by 

 different crustaceans, he showed that these metamor- 

 phoses always tend to impress upon the animal a 

 more and more special character, and that they suc- 

 ceed one another in a determinate order, the most 

 important being those which are the earliest mani- 

 fested. Thus, for instance, in the Isopods, a family 

 to which belongs the "Woodlouse (Oniscus), with 

 which every one is well acquainted, the young animal 

 first presents the peculiar characters of the family, 

 next it acquires those which determine the genus, 

 and lastly those which enable us to distinguish the 

 species. About the same time the celebrated German 



* We here only speak of the application of Embryology to the 

 improvement of the zoological method. We will postpone to a 

 future occasion a consideration of its anatomical and physiological 

 applications. 



