22 ERRORS ARISING FROM 



to the definition of a celebrated physiologist ( H ), and as 

 the word itself indicated with the Greeks and Romans, is 

 " that which is in perpetual growth and progress, and which 

 subsists in continual change of form and internal deve- 

 lopment." The series of organic types presented to our 

 view gradually gains enlargement and completenesses pre- 

 viously unknown regions are penetrated and surveyed, as 

 living organic forms are compared with those which have 

 disappeared in the great revolutions which our planet has 

 undergone, as microscopes have been rendered more per- 

 fect, and have been more extensively employed. Amid this 

 immense variety of animal and vegetable forms and their 

 transformations, we see, as it were, incessantly renewed the 

 primordial mystery of all organic and vital development, 

 the problem of metamorphosis, so happily treated by 

 Goethe, a solution corresponding to our intuitive desire 

 to arrange all the varied forms of life under a small 

 number of fundamental types. As observation, continually 

 increasing, reveals yet more and more of the treasures of 

 nature, man becomes imbued with the intimate con- 

 viction that, whether we regard the surface or the in- 

 terior of the earth, the depths of the ocean, or the 

 celestial spaces, the scientific conqueror will never complain 

 with the Macedonian, that there are no fresh worlds to sub- 

 ject to his dominion ( 12 ). General considerations, whether 

 relating to matter agglomerated in the celestial bodies, or to 

 the distribution of organic life on the surface of the earth, are 

 not only in themselves more attractive than special studies, 

 but they also offer peculiar advantages to the greater number 

 of men who can devote but little time to such occupations. 

 The different branches of the study of natural history are 



