88 Mr. Lindley's Account of the Spherical and 



the others are changed also), and those which do not depend 

 upon it are accidental. 



It must not however from this be understood that a system 

 is to be applied to one part only of its subject : on the contrary, 

 it embraces all parts, arranging them upon the same principles,— 

 but when they diverge in opposite directions, one is to be chosen 

 in preference to another. 



§ 15. Physical or Physiological marks are capable of distin- 

 guishing spheres (sections) of the highest order only; but in 

 those of the lowest they are always to be consulted. 



Physiological characters, as being those which are most essen- 

 tial, are little subject to variation, and therefore will not suffice 

 for distinguishing the lower spheres (orders, genera, species) ; 

 they are nevertheless to be continually consulted as to origin, 

 station, geographical distribution, &c. which illustrate the series 

 of affinities in various ways. 



§ 16. Essential characters are generally the most hidden, 

 and demand acute investigation ; the most superficial being 

 those which are accidental. 



Hence it is that accidental characters, or those of a lower order 

 are first seized, as being those which are most immediately under 

 our eyes: thus the low distinctions of species and varieties are 

 easily acquired by mere tyros, while the higher are within the 

 comprehension of masters of the science alone. 



The whole progress which has been made in natural history 

 has been a succession of triumphs of the more essential characters 

 over those accidental ones which had been previously received, 

 Thus in the following comparison, how much more impoitant 

 are those distinctions which are 



Essential than those which are Superficial. 



1. Mammalia, Amphibia, Pisces, 



of Linnaeus. 



2. Monocotyledones, Dicotyle- 



dones, &c. 



3. Hymenomycetes, Gastero- 



mycetes, &c. 



4. Lichens from their fruit. 



1. Quadrupeds, Serpents, Fishes, 

 of old authors. 



2. Trees, shrubs, herbs, &c. 



3. Fungi stipitati, sessiles, clavi- 

 formes. 



i: Lichens from their thallus. 



The foregoing proposition must not however be inverted, by 

 supposing that the more hidden characters are, the more essential; 

 Natural History would then become not only micrological, but 

 very difficult and erroneous. Where an object is easily distin- 

 guished by marks immediately under our eyes, microscopical dif- 

 ferences are not to be sought after. Besides, characters indicated 

 by highly magnifying microscopes are, in fact, as superficial as 

 those seen by the naked eye. 



§ 17. The primary powers of nature are arranged accord- 

 ing to the following laws. They are these : 



A. Ter- 



