320 ORIGIN OF CRYSTALLINE ROCKS. [XIII. 



extent, and common in most primary formations. The beds of 

 steatite, the still more extensive talcose formations, contain every- 

 where evidence of the same agents." Again, in 1854, in his Min- 

 eralogy, 4th edition (page 226), Professor Dana, after a complete 

 list of pseudomorphs, compiled from the writers of the school in 

 question, says : " These examples of pseudomorphism should be 

 understood as cases not simply of alteration of crystals, but in many 

 instances of changes in beds of rock. Thus all serpentine, whether 

 in mountain-masses or the simple crystal, has been formed through 

 a process of pseudomorphism, or in more general language, of metamor- 

 phism; the same is true of other magnesian rocks, as steatitic, tal- 

 cose, or chloritic slates. Thus the subject of metamorphism, as it bears 

 on all crystalline rocks, and of pseudomorphism, are but branches of one 

 system of phenomena." If there could be any doubt as to the mean- 

 ing of the words which I have italicized in quoting them from 

 Professor Dana, it is removed by his language in 1858. Then, as 

 now, adversely criticising my views on this question, he refers to 

 the statements above cited, made in 1845 and 1854, as expressions 

 of his doctrine, mentioning especially the first one, in which he 

 says, " metamorphism is spoken of as pseudomorphism on a broad 

 scale." (American Journal of Science (2), XXV. 445.) I confess 

 that I do not understand Professor Dana, when in his last criticism 

 of me, fourteen years after the one just quoted, he reproaches me 

 with having charged him with holding the doctrine that " regional 

 metaphorphism is pseudomorphism on a grand scale " ; and declares 

 that he makes no such remark, neither expresses the sentiment in 

 his Mineralogy of 1854. 



With these citations before us, and remembering the views of 

 Scheerer, and the later ones of Delesse, together with the language 

 of the latter in his essay on Pseudomorphs, let us notice the words 

 of Naumann, addressed to Delesse in 1861, in allusion to the essay 

 in question : " Permit me to express to you my satisfaction for the 

 ideas enunciated in your memoir on Pseudomorphs, ideas which 

 my friend Scheerer will doubtless share with myself" (id&s que mon 

 ami M. Scheerer partagera satis doute 'comme moi-meme). Then fol- 

 lows the language which I have quoted in my address, in which he 

 combats the error of those who hold that gneisses, umphiholites, 

 and other crystalline rocks are "the results of metainorphic epi- 

 X'in-sis, and not original rocks," and adds, "It is precisely because 

 pseudomorpltixiii hn-s so often been conftmnded with metamorjiltitm that 

 this error has found acceptance." (Bull. Soc. Geol. <!< France (2), 



