45 6 WHITMAN CROSS 



Concerning this treatment he remarks that it is the first time 

 that cosmic rocks have been given a place in a text-book of 

 petrography, but that it seems useful, for purposes of comparison, 

 to have them described in the same work with the terrestrial 

 rocks. 



H. Rosenbusch, i8yj. — Another important summary of the 

 results of the microscopical investigation of rocks appeared in 

 1877, under the title Mikroskopische Physiographie der niassigen 

 Gesteine, by H. Rosenbusch. There was in this work but slight 

 discussion of principles of classification, and the only new factor 

 of note in the system used is the idea expressed in the title, 

 which requires some explanation. All rocks were divided into 

 two classes : 



I. Massive rocks ("Massige Gesteine"). 

 II. Stratified rocks (" Geschichtete Gesteine"). 



A class of Metamorphic rocks was not considered feasible. 



" Massive " and " stratified," as used by Rosenbusch in this 

 connection, do not refer to rock textures, as one might suppose 

 from the historic use of the terms ; for this primary division was 

 avowedly intended to express an idea, first brought out by 

 Lossen (which will be referred to more fully in a later section of 

 this review), that the most important relation of rocks is the 

 formal one to the earth sphere. Rocks may be considered as 

 having been formed, either at the surface under the influence of 

 gravity, in more or less concentric shells or strata, or, in eruptive 

 bodies of irregular shape and position not determined by gravity. 

 Under this conception all rocks are either stratified or massive. 

 Massive rocks in this sense are also eruptive rocks, but Rosen- 

 busch chose to use the former term in systematic petrography 

 because free from the genetic conception involved in the latter. 

 In view of the evolution of this master's ideas, presented in 

 later works, his language will be quoted : x " The former name is 

 to be preferred because it refers only to an undeniable form of 



'"Der erste Name ist vorzuziehen, weil er sich lediglich auf eine unlaugbare 

 Erscheinungsform bezieht und keinerlei irgendwie geartetes Prajudiz iiber die genet- 

 ischen Verhaltnisse involvirt." 



