MODERN METHODS OF CLASSIFICATION CHARACTERIZED. 49 



The present lithological methods of classification can best be character- 

 ized, in a homely way, by supposing that there were placed in the hands of 

 a zoiilogist a great number of specimens of one species of some carnivorous 

 animal, in every condition, from a fresh state to that of an advanced stage 

 of decomposition ; also of those of the same species that had lived during 

 distinct periods of time, as well as of those that had lived for different 

 lengths of time. With these, too, let there be given to the zoologist a 

 number of packages of the bones of this animal, part of the bones having 

 been worn and part unworn. 



Now, imagine this zoologist naming as new species every specimen more 

 decomposed than a preceding one ; as new species, those which showed 

 different products of decomposition ; as new species, those that gave any 

 variation, through that decomposition, upon chemical analysis — as for 

 instance, one and forty-seven one hundredths, or even nine-twentieths of 

 one per cent. Continuing, let it be supposed that our zoologist makes new 

 species, or at least varieties, out of all specimens in which he finds any teeth 

 or bones of other animals which have been swallowed ; changing the species 

 or variety as often as the inclosed fragments differ ; creating new species 

 out of all that have lived for different lengths of time ; new species out of 

 those whose bones are fractiu-ed crosswise, as distinct from those whose bones 

 are broken lengthwise ; new species out of the distinct packages of frag- 

 ments ; new species according as these fragments are worn or angular; 

 also, above and beyond all, fixing an arbitrary date, and demanding that 

 all the specimens of this animal that had existed prior to that time should 

 be held as distinct species, and in general of different origin from those that 

 were of a later period. Suppose, too, that in addition, our zoologist should 

 maintain that some, or all, of the animals submitted to him were made 

 out of the remains of their defunct ancestors, by a species of fermen- 

 tation ; also, that this creative chemical action was brought about by the 

 deposition of the more recent remains upon the older, and that then the 

 older forms successively came from beneath and lay down on top, thus pro- 

 ducing a perpetual cycle. Let the reader suppose all this and he will gain 

 some idea of the principles and methods commonly employed in lithology, as 

 well as, in a greater or less degree, in chemistry as applied to rocks. 



This is no mere fancy sketch, but, so far as can be done by taking an 

 illustration from a distinct science, shows some of the principles of lithology 

 as taught to-daf/, and some of the methods upon which rocks, even now, are 

 classified. 



