TEST OF THE NEBULAR HYPOTHESIS 73 
Following a purely naturalistic and inductive method, it 
would seem that the spiral nebula, whose abundance is attested 
by the recent notable success of Professor Keeler in photograph- 
ing numerous small ones, offer the greatest inherent presump- 
tion of being the ancestral form. While present knowledge of 
their dynamics is almost inappreciable, the suggestions of their 
forms and the distribution of their matter do not seem neces- 
sarily incompatible with the criteria deduced in this inquiry. 
Both these suggestions are obviously very immature, and 
have their sole justification in a natural reluctance to offer 
destructive results only —a reluctance intensified by an acute 
consciousness that the hypothesis against which they are directed 
is perhaps the most beautiful and fascinating ever offered to the 
‘scientific public. 
T. C. CHAMBERLIN. 
