S8 Professor Mohs's General Reflections on Mineralogy. 
the genus might be conducted, we should have no genera in the 
mineral kingdom ; that is to say, the idea of the natural-histori- 
cal genus would not be applicable to this kingdom. 
The erroneous ideas that have prevailed in regard to the di- 
vision of genus in Mineralogy, and partly also in Zoology and 
Botany, have been the cause that this was considered to be the 
case with regard to the first of these sciences, from reasons simi- 
lar to those which rendered the existence of the species, and even 
of the individual, a matter of dispute. The genus of Natural 
History is nothing more nor less than the similarity of several 
species , which is much greater among some of them than among 
others. Vegetable and animal species, which resemble each other 
to such an extent, are accounted as species belonging to the same 
genus, and the determination of the genus does not depend upon 
any other consideration. Upon the same foundation, also, must 
it be grounded in the mineral kingdom, because Mineralogy, in- 
asmuch as it is a part of Natural History equally with Zoology 
and Botany, must proceed upon the same principles with them. 
So many species have already been discovered in the mineral 
kingdom, that their existence, or the applicability of the idea of 
genus in Mineralogy, can no longer be disputed. They are not, 
perhaps, all determined with perfect exactness ; for this depends 
upon experience, which can at no time be said to be entirely ex- 
hausted ; nor can this subject be more particularly considered 
in the present place, as we are here exclusively confined to the 
general development of the principles of Natural History, and 
their application to nature. But it is necessary to advert to an- 
other point of view from which the determination of the genus 
may be considered, because, if the objections dependent upon it 
were founded, this determination would, in fact, be annihilated. 
The idea of that kind of resemblance which may be called the 
natural-historical one, is said to be vague and undetermined ; 
so that we cannot indicate upon what it depends. It is subject 
to a latitude of intensity, and is therefore expressed in different 
degrees ; and, what is worst of all, it does not yield a constant 
rule, according to which some one or other individual might, in 
every case, be referred to a certain genus, or excluded from it. 
These objections we now proceed to remove. 
( To be continued.) 
