1823.] the natural Distribution of Imects and Fungi, 331 



break the parallelism of corresponding groups,— or we may- 

 account every group as divisible into five, and thus not only 

 agree with M. Fries's observations, but besides keep the parallel- 

 ism of analogies uninterrupted. If in this state of the matter it 

 could now be shown, that in the animal kingdom the same law 

 is followed by nature ; in short, to take an instance, if it could 

 be proved that the Ammlo^a may either be divided into four 

 groups, viz. Ametabolay Crustacea, Arachnida and Ptilota, where 

 this last is remarkably capacious and divisible into two natural 

 groups, viz. Mandibulata and Haustellata, or that annulose 

 animals may be divided at once into five groups of the same 

 degree, but of which two have a greater affinity to each other 

 than they have to the other three — if, I repeat, this could be 

 proved, should we not be justified in affirming that the rule, so 

 far as concerns Insects and Fungi, is one and the same ? The 

 possibihty of thus distributing the annulose animals has, how- 

 ever, been demonstrated already in the Horcc Entomoiogice ; 

 and it is the way in which we ought to take the rule that only 

 now remains to be investigated. In short, since only two 

 methods * have yet been found to coincide with facts as pre- 

 sented by nature, the question is, whether we ought to account 

 Fungi as divisible into five groups, or into four, of which one 

 forms two of equal degree. Now I think it may without diffi- 

 culty be shown, from our author's own observations and rules, 

 that there is only one determinate number which regulates the 

 distribution of Fungi, and that five is this number. 



In the first place, M. Fries lays it down as a rule, which is 

 quoted above, that he admits no groups whatever to be natural 

 uriless they form circles more or less complete. Let us then 

 apply this rule to what he terms his central group, and which he 

 makes always to consist of two. Does this form a circle ? If 

 not, the group cannot be natural according to his own defi- 

 nition. 



If, on the other hand, its two component groups are each 

 circles, then these are natural. Thus the Ptilota will not form 

 one circle, but two ; consequently they form two natural groups, 

 which is furthermore proved by their parallel relations of ana- 

 logy. If we turn to Fungi also, the Hymenini, according io 



• The number seven might also perhaps, for obvious reasons, occur to the mind, 

 were it allowable in natural history to ground any reasoning except upon facts of organ- 

 ization. The idea of this number is however immediately laid aside, on endeavouring 

 to discover seven primary divisions of equal degree in the animal kingdom. It is easy, 

 indeed, to imagine the prevalence of a number ; the difficulty is to prove it. The 

 naturalist, therefore, requires something more than the statement of a number, before 

 he allows either a preconceived opmion or any analogy not founded on organic struc- 

 ture to have an influence on his favourite science. He requires its application to nature 

 and its illustration by facts. As yet, however, no numbers have been shown to prevail 

 in natural groups but five, or, which is the same thing, four of which one group is di- 

 visible into two. Perhaps, indeed, the most clear method of expressing ourselves on 

 tliis subject is to say that, laying aside osculant groups, every natural group is divisible 

 into five, which always admit of a binary distribution, that is, into two and three. 



