500 ANIMAL NATURE OF DIATOMEiE. 



want a measure for the fraction into which time, as well 

 as space, is naturally divided. 



It is true that, in the study of nature, we ought to 

 proceed independently and abstractedly of any precon- 

 ceived idea, attending to phenomena only; but still it is 

 necessary to select these phenomena one from another, 

 to compare them, to separate those they possess in com- 

 mon, and those in which they differ, thus gradually 

 ascending to synthesis. Every metaphysical idea, as- 

 sumed a priori as the basis of a doctrine, is of necessity 

 arbitrary. But synthesis, logically executed and preceded 

 by the analysis of individual facts, leads us securely to 

 the attainment of knowledge. There may be error in the 

 observation, or in the deduction, but never in the method. 



When Kiitzing, combating the principle of the exis- 

 tence of a precise limit between the animal and the plant, 

 concludes that there exists no such limit, he only substi- 

 tutes one metaphysical principle for another, and therefore 

 wanders from the maxims laid down by himself just 

 before. 



When he demonstrates that movements, and the 

 organs by which these are performed, are not exclusively 

 those of animals, and that there may be an appearance 

 of an eye, a stomach, and a mouth, in vegetables, he 

 controverts his own theory of a double nature, animal and 

 vegetable, in the same being. 



The observed facts are valuable. They prove the 

 insufficiency of the characteristics given by authors to 

 distinguish animals from plants. And, even if it should 

 remain impossible for our most remote posterity to 

 decide, whether given beings can, or ought to be included 

 in the abstract idea of a plant, or in that of animal, this 

 will not suffice to confound the two ideas, because their 

 empirical nature is relative, indeed, but not arbitrary. 



Perhaps the most important observation of Kiitzino-, 

 on this subject, is that of the different vital phenomena 

 presented by the most simple vegetables, according to 

 the prevalence in them of the external gelatinous (cellulose) 



