ANIMAL NATURE OF DIATOMEjE. 461 



those that are free ; which last, conditions being equal, 

 are superior to all the rest. 



Regularity, then, and symmetry of form appear to me 

 characteristic of inferiority, nor do I consider new argu- 

 ments necessary to maintain a principle which is univer- 

 sally adopted in all natural classifications. 



I am sorry to repeat here what I have said so often 

 already, that we are entirely wanting in true data to judge 

 of the affinities of Diatomeae, among themselves as well as 

 with other beings, and of the degree of their organic 

 complication ; for we are completely ignorant, as it were, 

 of what this organisation is. And as to this, Kiitzing 

 only informs us that the internal substance, which he 

 terms gonimic, extends itself in a thin strip {fettuccia) 

 along the secondary surfaces, then divides itself trans- 

 versely in the middle, and finally contracts itself into one, 

 two, or rarely more globular portions {grumi). We have 

 already found contrary to the opinions of Ehrenberg, 

 some more important particulars respecting the Naviculse. 

 Nor have we anything different to add, generally, as to 

 all the family. 



The Naviculese, together with the two preceding 

 families (Cymbellese and Gomphonemese), constitute the 

 group of Distomaticse, a group characterised solely by 

 the organic condition indicated by the name, and. which 

 we have so often found to be wanting. 



The other two families (Cocconoidese and Achnanthese) 

 which, comprehended under the name of Monostomaticse, 

 constitute, in union with the preceding, the grand division 

 of Stomatic8e — appear to be much more nearly allied. 

 The entire system, I am obliged to repeat, is constructed 

 upon isolated and inconstant characters, and on that 

 account cannot fail to be vacillating. But it is equally 

 necessary to allow that, in the actual state of science 

 it would have been difficult to do better ; and we must 

 also regard it as a principle suggested by sound reasoning, 

 to attribute great importance to the presence or absence 

 of the central aperture in one or both of the secondary 



