320 THEORY OF THE SYSTEM. . 



dual still remains octahedral Fluor-haloide. For if we sup- 

 pose a number of individuals, to agree with each other in 

 all their properties, excepting their forms, these however 

 not being members of the same series ; we are not entitled 

 to apply to them the above process ; because the differences 

 existing among them cannot be removed or made to dis- 

 appear by the idea of a series, and accordingly the indi- 

 viduals themselves cannot be brought under the idea of 

 identity. The degree of difference (. 216.) between such 

 individuals is therefore much higher than it would be, if 

 under the same circumstances the forms were members of 

 the same series. 



As an example of the latter case, we may quote the hexa- 

 hedral and the prismatic Iron-pyrites. There exist indivi- 

 duals in these two species exactly agreeing with each other in 

 every one of their natural-historical properties, except their 

 crystalline forms. But as these forms belong to different 

 systems, and are therefore incompatible with each other, 

 the difference between the individuals appears greater than 

 it would be, if the forms should belong to the same series. 



The process explained in the members of the series of 

 crystalline forms, naturally applies likewise to every pro- 

 perty, from the gradual differences of which series arise. 

 Thus we are provided with the means of discovering such 

 individuals, as, though not absolutely identical, may yet 

 be brought under the idea of identity, and of separating 

 them from all the rest. Such individuals might be col- 

 lected under particular ideas ; but such ideas would be 

 of little use, on account of their very limited application to 

 experience. Nevertheless they lead the way to that idea, 

 which it is the particular object of the present inquiry, to 

 develope according to the principles of Natural History. 



. 219. CONNEXION OF SEVERAL SERIES OF INDIVI- 

 DUALS. 



An individual which, on account of its form and 

 the rest of its natural-historical properties, is a 



