Voi,. 6, 1920 
PETROLOGY: G. P. MERRILL 
451 
nicols break up into several illy defined areas over which the dark cloud 
sweeps faintly and irregularly as the stage revolves. The material seems 
to be a partially devitrified glass in a condition of optical stress as from 
FIG. 1 
sudden cooling. Chondrules of this type and those next to be described 
more nearly resemble the spherulites of the terrestrial rocks than any 
others which have come under my notice. Their outlines are at times 
as sharply demarked from the matrix in which they are embedded as are 
FIG. 2 
the spherulites in the rhyolitic obsidians of the Yellowstone National 
Park. 
Chondrules of the radiating type are shown in figures 3, 4 and 5, from the 
