1 94 Morphology and Systematic Botany under [BOOK i. 



sistency of reasoning than Schleiden, and in entire accordance 

 with the nominalist view of genuine investigation of nature in 

 its sternest opposition to the idealistic school, Nageli's first 

 principle is not only to deduce conceptions from the observation 

 of phenomena, to classify them and establish their subordin- 

 ation, but to treat these conceptions as mere subjective pro- 

 ducts of the understanding and employ them as instruments 

 of thought and communication, and to be always ready to 

 modify them as soon as inductive enquiry renders such modi- 

 fication necessary. Till this happens, the conception once laid 

 down and connected with a word is to be strictly adhered to, 

 and every arbitrary change or confusion with another concep- 

 tion is strictly forbidden. Since in nature everything is in 

 movement, and every phenomenon is transitory, presenting 

 itself to us in organic life especially as the history of develop- 

 ment, all due regard must be paid to this condition of con- 

 stant motility in forming scientific conceptions. The history 

 of development is not merely to be treated generally as one 

 of various means of investigation, but as identical with inves- 

 tigation into organic nature. These views are expressed in 

 Nageli's detailed observations on method in the first and 

 second volume of the journal which he brought out in con- 

 junction with Schleiden in 1844 and 1855, where the chief 

 hindrance to his carrying them out fully and consistently is 

 also to be found; for, like all his contemporaries, Nageli be- 

 lieved at that time in the constancy of species, and consistently 

 with this view he looked upon the natural system as a frame- 

 work of conceptions, though these do not take the form of 

 Platonic ideas with him as with the systematists of the idealistic 

 school. It is equally consistent with his philosophical posi- 

 tion, which refused to regard a change in our conceptions as 

 a change in things themselves, that ' the idea of metamor- 

 phosis ' in the sense of Goethe and Alexander Braun disap- 

 pears in Nageli from the field of scientific observation. It has 

 been shown in the previous chapter that what Goethe called 



