388 Ia. a. DALY METAMOKPillS.M AM) ITS PHASES 



Iiiternatioiml Dictionary (190^), Ilatcli (1909), Eosenbuscli (1910), 

 Scott (1911), Becke (1911), Linclgren (1913), and probably Zirkel 

 (1893). 



3. Authors formally defining nietaniorphisni in the broader sense, but 

 in actual practice excluding weatbering processes, are: cle Lapparent 

 (1893), Men-ill (1897), Pirssou and Scliucliert (1915), F. W. Clarke 

 (1916), andLabee (1916). 



-1. Autliors exciiiding froni the delluition both cementation and weailiei'- 

 ing are: Lyell (1838), Cliaml)erlin and Salisbury (1906), Ilaug (1907), 

 Flett (1911), Tornquist (1913), Boeke (1915), and Cleland (1916). 



5. Authors defining metamorphism in a broad sense and also in a nar- 

 rower sense (excluding at least weathering processes) are : Studer (1817), 

 Naumann (1850), Delesse (1857), Prestwich (1886), Grubenmann 

 (1910), and Eies and Watson (1915). 



'None of the long list of writers has been guided by the strict logic of 

 the literal etymology. In no case has rock folding been included among 

 the metaniorphic pi'ocesses, though the mere folding of beds is a manifest 

 transformation in a most literal sense. Thus, without exception, geol- 

 ogists have appreciated the uselessness of "metamorphism,^^ if that word 

 be given its broadest possible meaning. 



Their right to restrict its meaning, in the interests of clear thinking 

 and writing, is abundantly illustrated in the history of words. For tlie 

 navigator, '^chronometer" has not its literal meaning, but applies only to 

 a very small class of time-keepers. ' Astronomers arbitrarily exclude 

 comets and stars from the class of planets, the "wanderers." The arclii- 

 tect's "dome," a synonym of "cupola," has only an indirect relation to 

 the original Greek word, for the Greek house or temple w^as not in cupola 

 form. The crystallographic "dome" is no more thoroughly entrenched in 

 the English language because it recalls the actual form of the Greek 

 domes. In zoology the meaning of ^'mollusk" is universally restricted 

 far within tlie limits set b}^ its etjmiology, and "metamorphosis'' itself is 

 as narrowed for technical biology as "metamorphism" has been naiM-o\\ed 

 by Lyell and many of his successors. 



The degree to which strict etymology should be disregarded is, ilien, 

 clearly a question of expediency. That it is difficult to answer in a way 

 to win general consent is obvious to the student of definitions in the latest 

 textbooks, dictionaries, and Government reports. The history of opinion 

 (hiring earlier decades is also somewhat discoui'aging : yet a ciKica.I com- 

 parison of the older and newer writings seems to suggest a way out oC 

 the present confusion. 



In the first i)lace, the great majority of geologists have, Avith Lyell him- 



