392 Scientific Intelligence. 
Il. Grotoegy AND NaAtuRAL HIstToryY. 
. Untersuchungen tiber die Entstehung der altkrystallinen 
Schiefergesteine mit besonderer Bezugnahme a iichsische- 
bodily 
ing 159 eee ake representations of rock structures, Bonn: 
ey Z ( 4 bad 
ob 
result of nine years of careful work, the skillful arrangement of 
this material so as to lead logically to the conclusions reached, 
enormous pressure may produce. Heim and others in Switzer 
land have shown that, when enclosed on all sides, even rocks 
may be moulded like a viscous mass. Lehmann advocates rather 
a plasticity, like that of wet clay, produced by a crushing and 
sliding of the smallest particles upon each other and a re-cement- 
ing by abundant mineral secretions. In this manner, 4 tightly 
schists. As 
so Dr. Lehmann considers schistose structure in a crystalline rock 
as no evidence whatever of sedimentation. He therefore agrees 
with Naumann in considering the Saxon granulite area of erup- 
