13 



does it readily appear how nature could otherwise express affinity. 

 For what is affinity, if it be not the universal harmony of charac- 

 ters ? If one organ is changed, we know another is always dis- 

 turbed , if one is more perfect, another becomes less so. No change 

 in the organs is unimportant. Whenever the system is perfect, all 

 parts will explain each other, and the place of every object in the 

 system will be indicated not only, but demonstrated. And on the 

 other hand its place in the system will indicate the nature and char- 

 acters of the object much more than its description. (It seems pos- 

 sible to express this by formulae, by which, by the change of a sin- 

 gle letter, all the differences of Agaricus are indicable, as see ap- 

 plied in the Consp. Syst. Mycol.) Every section which pre- 

 sents the organ the type of the section most perfectly developed, 

 so that this section shall excel or often exclude all the rest of the 

 sections, is called Centrum. It is evident that this must be most dis- 

 tinct from the other sections, and moreover that its relations with 

 the other essential organs must be less altered, so that species in 

 the centre will approach each other more nearly in resemblance. 

 We find, then, that central genera, the types of orders, are always 

 vast (Agaricus; Fucus; Lichen in the sense of Wahlenberg ; 

 Hypnum, &c.), and are divided into more genera with much greater 

 difficulty than the radii, which are sections (whether they be genera 

 Or orders) which pass from the one to the other. These centres are 

 the foundations of the whole system. The character of a class, 

 then, will square best with the centre, and less perfectly with the 

 radii, which recede toward other classes. The system expresses 

 everywhere radii everywhere touching. The centre passes always 

 into two series, an inferior and a superior, whereof the former more 

 evidently approaches the preceding, and the latter the following 

 class. (These latter principles are laid down by the author with 

 reference to his system of the Fungi ; they are, however, general, 

 if rightly, that is ideally, taken.) The differences of Affinity and 

 Analogy should be stated, dffines, then, are those which follow in 

 the same series, and seem mutually to pass into each other. Jlnal- 

 oga, those which occupy parallel places in different series, and mu- 

 tually correspond to each other. Labiate and Personatse are anal- 

 ogfB ; Labiate and Asperifolise, affines. PotentillesB and Ranunculeae 

 are analogtR. (Many other illustrations given.) The more natural- 

 ists have given in to a superficial observation, the more they have 

 confounded analogy with affinity. These differences are exempli- 

 fied in every province of natural history. 



These are some of the principles of the Systema Mycologicum, 

 as they are displayed by the author. The skill with which they are 

 applied, and the completeness with which the whole is set forth, are 

 acknowledged by botanists. Such a trial of a system is most severe, 

 and to me it is reasonable to doubt if any system will stand it. The 

 truth, indeed, is eternal, but not the words which limit or express 

 it, not the principles necessarily, nor their systematic construction. 

 I would regard, then, the above only as suggestive ; and so once 

 again return to nature. 



The next general work of Fries was his " Systema Orbis Vege- 



