PLATE VIII. 



Pig. 1. — riiKher K, level. Slit at "032. Though taken before the photographs 

 reproduced in IMate VII, this ])ictiire further eui!»hasizes the differences noted at 

 lower levels. The fact that the changes are ])rogre.ssive largely eliminated the 

 time element, which might otherwise l)e suspected of causing the observed dif- 

 ferences. As a matter of fact, these Hocculi are ciuiescent and slowly changing, 

 differing very decidedly from eruptive jthenomena. 



J"iG. 12. — Ko level. Slit at ?.'.i:5:5.S. Here the calcium vapor is very brilliant 

 and covers a larger area. The photograph contains distinct evidtMice of dark 

 absorbing masses at higher levels. Perhaps the best instance of this is the dark 

 tongue which runs somewhat north of west from the small spot south iireceding 

 the largest one (jf the group. This tongue seems to form a part of an extensive 

 dark area, which completely surrounds the bright tlocculi of the group. 



153 



